1 00:00:00,000 --> 00:00:00,740 2 00:00:00,740 --> 00:00:05,370 Let's say I have a line, let me make it a straight line. 3 00:00:05,370 --> 00:00:08,060 And the equation of that line, since it's running in the 4 00:00:08,060 --> 00:00:10,320 horizontal direction is going to be y is equal 5 00:00:10,320 --> 00:00:11,656 to some constant. 6 00:00:11,656 --> 00:00:12,970 So let me write that. 7 00:00:12,970 --> 00:00:17,010 So the equation of this line right here is y is equal to k. 8 00:00:17,010 --> 00:00:19,760 And let's say I have some other point. 9 00:00:19,760 --> 00:00:23,650 I'll call that-- well, we'll call that a focus because 10 00:00:23,649 --> 00:00:25,885 it will be a focus. 11 00:00:25,885 --> 00:00:29,890 And let's say that point-- let's put it right here-- is 12 00:00:29,890 --> 00:00:36,299 it the coordinate, let's call it a comma b. 13 00:00:36,299 --> 00:00:40,914 And let's think about the set of all points or the locus of 14 00:00:40,914 --> 00:00:44,369 all points that are equidistant to this point right 15 00:00:44,369 --> 00:00:46,719 here and this line. 16 00:00:46,719 --> 00:00:48,799 Just so you get the terminology we'll call 17 00:00:48,799 --> 00:00:50,769 this line a directrix. 18 00:00:50,770 --> 00:00:52,500 Let me write that down. 19 00:00:52,500 --> 00:00:57,049 Directrix, it's probably a word you've never heard before. 20 00:00:57,049 --> 00:00:59,640 And frankly, I've never heard it outside of the context 21 00:00:59,640 --> 00:01:04,189 of parabolas or conic sections in general. 22 00:01:04,189 --> 00:01:05,149 So let's call that a directrix. 23 00:01:05,150 --> 00:01:08,090 This is our focus. 24 00:01:08,090 --> 00:01:11,150 And what we want to do is we want to find all of the points 25 00:01:11,150 --> 00:01:15,590 in the xy-plane that are equidistant to this focus 26 00:01:15,590 --> 00:01:16,560 and this directrix. 27 00:01:16,560 --> 00:01:19,090 So there's one point that just by looking at it we could say 28 00:01:19,090 --> 00:01:22,162 is going to be in our locus. 29 00:01:22,162 --> 00:01:26,060 So it's going to be right there because clearly, this point is 30 00:01:26,060 --> 00:01:28,750 equidistant; it's halfway between that point 31 00:01:28,750 --> 00:01:30,379 and this line. 32 00:01:30,379 --> 00:01:31,500 Now let's see what other points. 33 00:01:31,500 --> 00:01:34,900 There will probably be this point right here because the 34 00:01:34,900 --> 00:01:38,170 distance from there to there is this name as the distance 35 00:01:38,170 --> 00:01:40,409 from if you just drop a line straight down. 36 00:01:40,409 --> 00:01:42,329 Remember, we want to get the shortest distance between 37 00:01:42,329 --> 00:01:43,379 this point and the line. 38 00:01:43,379 --> 00:01:48,379 We could have said something like this distance, but this 39 00:01:48,379 --> 00:01:50,369 distance wouldn't be the shortest distance between 40 00:01:50,370 --> 00:01:51,250 this point and this line. 41 00:01:51,250 --> 00:01:54,250 So you would go straight down to the line there. 42 00:01:54,250 --> 00:01:57,920 Likewise, this point would be there. 43 00:01:57,920 --> 00:02:00,960 So that distance is the same as that distance. 44 00:02:00,959 --> 00:02:04,419 And you can already, I think, begin to imagine 45 00:02:04,420 --> 00:02:05,579 the type of shape this is. 46 00:02:05,579 --> 00:02:07,959 And if you look at the title of this video you can probably 47 00:02:07,959 --> 00:02:08,989 guess where this is going. 48 00:02:08,990 --> 00:02:14,629 That the shape is going to look something like this. 49 00:02:14,629 --> 00:02:18,319 Or something pretty similar to what we know as a parabola. 50 00:02:18,319 --> 00:02:19,799 And actually, it will be a parabola. 51 00:02:19,800 --> 00:02:22,000 There's no mystery there. 52 00:02:22,000 --> 00:02:23,740 But what we're doing this in this video is actually show 53 00:02:23,740 --> 00:02:24,534 you that is a parabola. 54 00:02:24,534 --> 00:02:26,569 Show it to you mathematically instead of this 55 00:02:26,569 --> 00:02:27,419 little drawing here. 56 00:02:27,419 --> 00:02:29,389 Where I show you that it kind of looks like it would be a 57 00:02:29,389 --> 00:02:34,750 parabola because this distance right here looks about the same 58 00:02:34,750 --> 00:02:37,509 as that distance right there. 59 00:02:37,509 --> 00:02:39,750 I could keep going up and down the curve and keep doing that, 60 00:02:39,750 --> 00:02:41,080 but that's not satisfactory. 61 00:02:41,080 --> 00:02:45,830 Let's actually mathematically show that the locus of all 62 00:02:45,830 --> 00:02:49,300 points that are equidistant to this point and this line-- this 63 00:02:49,300 --> 00:02:53,320 focus and this directrix-- is in fact, a parabola. 64 00:02:53,319 --> 00:02:56,870 So let's say I have some point that's in this locus and let me 65 00:02:56,870 --> 00:03:01,710 call the point here-- let me do it in a different color because 66 00:03:01,710 --> 00:03:04,570 it's the same color as my directrix-- x, y. 67 00:03:04,569 --> 00:03:07,979 So I want to find all of the x, y's-- all of the points that 68 00:03:07,979 --> 00:03:13,219 satisfy an equation where their distance to the focus is equal 69 00:03:13,219 --> 00:03:14,590 to their distance to the directrix. 70 00:03:14,590 --> 00:03:17,479 So what's the distance between x, y and the focus? 71 00:03:17,479 --> 00:03:19,789 What's this distance right here? 72 00:03:19,789 --> 00:03:20,949 d sub 1. 73 00:03:20,949 --> 00:03:23,075 Well, we just used the distance formula. 74 00:03:23,075 --> 00:03:26,656 It's x minus the x-coordinate of the focus. 75 00:03:26,656 --> 00:03:30,349 So it's x minus a squared. 76 00:03:30,349 --> 00:03:33,250 So the difference in the x's squared. 77 00:03:33,250 --> 00:03:38,365 Plus the difference in the y's squared-- y minus b squared. 78 00:03:38,366 --> 00:03:40,690 The square root of that. 79 00:03:40,689 --> 00:03:42,810 So this is the distance to the focus. 80 00:03:42,810 --> 00:03:44,310 So I'll call that d sub 1. 81 00:03:44,310 --> 00:03:46,870 That's this distance right there. 82 00:03:46,870 --> 00:03:49,830 And we want to find all of the x and y's where the distance to 83 00:03:49,830 --> 00:03:53,320 the focus is equal to the distance to this 84 00:03:53,319 --> 00:03:54,969 line right there. 85 00:03:54,969 --> 00:03:59,729 So if we call this distance-- let's call this the d sub 2-- 86 00:03:59,729 --> 00:04:01,479 the distance to the directrix. 87 00:04:01,479 --> 00:04:05,389 So the distance to the focus is going to be equal to d sub 2. 88 00:04:05,389 --> 00:04:07,699 And d sub 2, what's this going to be equal to? 89 00:04:07,699 --> 00:04:11,789 Well, it's just the difference in y because no matter where we 90 00:04:11,789 --> 00:04:15,250 are we're just going to drop down straight to the directrix. 91 00:04:15,250 --> 00:04:20,399 So the difference in y-- I could just say y minus k. 92 00:04:20,399 --> 00:04:22,179 That would be the difference in y. 93 00:04:22,180 --> 00:04:25,620 But in this case I did make it so that the coordinate up here 94 00:04:25,620 --> 00:04:27,689 is higher than the k over here. 95 00:04:27,689 --> 00:04:30,420 But what if we had a situation where this point was 96 00:04:30,420 --> 00:04:31,280 below this line? 97 00:04:31,279 --> 00:04:33,439 I mean, there's nothing here that I said that we can only 98 00:04:33,439 --> 00:04:34,930 deal with points above this line. 99 00:04:34,930 --> 00:04:36,930 We haven't proven that to ourselves yet. 100 00:04:36,930 --> 00:04:39,019 So to make sure that this distance is positive we could 101 00:04:39,019 --> 00:04:41,349 take the absolute value or we could just square it and 102 00:04:41,350 --> 00:04:42,910 then take the square root. 103 00:04:42,910 --> 00:04:45,020 And then that ensures that we're not dealing with 104 00:04:45,019 --> 00:04:46,560 negative distances. 105 00:04:46,560 --> 00:04:50,589 So here we set up the equation for all of the x's and y's 106 00:04:50,589 --> 00:04:54,399 where the distance to the focus is equal to the distance 107 00:04:54,399 --> 00:04:54,939 to the directrix. 108 00:04:54,939 --> 00:05:00,069 And let's see if this actually turns out to be a parabola. 109 00:05:00,069 --> 00:05:02,750 So the first thing we can do is we can square both sides and 110 00:05:02,750 --> 00:05:05,660 get rid of the radicals. 111 00:05:05,660 --> 00:05:10,010 So we get x minus a squared. 112 00:05:10,009 --> 00:05:11,159 Radicals aren't good. 113 00:05:11,160 --> 00:05:13,730 Well, I don't want to make any social commentary. 114 00:05:13,730 --> 00:05:20,340 So x minus a squared plus y minus b squared is equal to 115 00:05:20,339 --> 00:05:26,619 the square root of the other side-- y minus k squared. 116 00:05:26,620 --> 00:05:28,540 And right now, at least, it looks like there's going to be 117 00:05:28,540 --> 00:05:31,120 some y squared terms and I mean there's definitely 118 00:05:31,120 --> 00:05:31,579 an x squared term. 119 00:05:31,579 --> 00:05:33,419 That doesn't seem like it's a parabola right now. 120 00:05:33,420 --> 00:05:37,000 But let's keep going forward. 121 00:05:37,000 --> 00:05:40,584 This is x minus a squared. 122 00:05:40,584 --> 00:05:43,649 And then let me square these-- actually, expand 123 00:05:43,649 --> 00:05:45,729 these two binomials. 124 00:05:45,730 --> 00:05:55,560 So plus y squared minus 2yb plus b squared is equal to y 125 00:05:55,560 --> 00:06:01,600 squared minus 2yk plus k squared. 126 00:06:01,600 --> 00:06:03,020 Now what can we do to simplify this? 127 00:06:03,019 --> 00:06:05,959 Well, we have a y squared here and we have a y squared 128 00:06:05,959 --> 00:06:07,459 on the right-hand side. 129 00:06:07,459 --> 00:06:09,259 So we can subtract y squared from both 130 00:06:09,259 --> 00:06:11,242 sides of the equation. 131 00:06:11,242 --> 00:06:14,520 They cancel out, and then we got rid of the y squared so all 132 00:06:14,519 --> 00:06:16,579 of a sudden this is starting to look a lot more like a parabola 133 00:06:16,579 --> 00:06:21,259 because this is now an equation that relates y's 134 00:06:21,259 --> 00:06:22,170 to an x squared. 135 00:06:22,170 --> 00:06:25,250 So let's clean this up and actually make sure that we can 136 00:06:25,250 --> 00:06:26,860 get it in a form that we normally associate 137 00:06:26,860 --> 00:06:28,210 with a parabola. 138 00:06:28,209 --> 00:06:34,459 So we now have-- I'll just rewrite it-- x minus a squared 139 00:06:34,459 --> 00:06:42,259 minus 2yb plus b squared is equal to minus 2yk 140 00:06:42,259 --> 00:06:45,779 plus k squared. 141 00:06:45,779 --> 00:06:46,250 Now what can we do? 142 00:06:46,250 --> 00:06:48,550 Let's take all the y's and the constants on one 143 00:06:48,550 --> 00:06:49,860 side of the equation. 144 00:06:49,860 --> 00:06:53,660 So if we move both of these terms onto the right-hand 145 00:06:53,660 --> 00:06:56,260 side, so we want to add 2yb to both sides. 146 00:06:56,259 --> 00:07:01,969 So we get x minus a squared is equal to-- I'm moving both of 147 00:07:01,970 --> 00:07:03,845 these terms to the right-hand side. 148 00:07:03,845 --> 00:07:07,740 So if we add 2yb to both sides then we'll have a positive 149 00:07:07,740 --> 00:07:09,490 2yb on the right hand side. 150 00:07:09,490 --> 00:07:17,670 So 2yb, and then we'll have that minus 2yk right there. 151 00:07:17,670 --> 00:07:21,520 And then we're subtracting b squared from both sides. 152 00:07:21,519 --> 00:07:27,719 So it's minus b squared plus k squared. 153 00:07:27,720 --> 00:07:31,330 I just arbitrarily decided to write whatever I transferred 154 00:07:31,329 --> 00:07:33,709 from the left-hand side to the right-hand side in magenta 155 00:07:33,709 --> 00:07:35,589 just so maybe it makes it a little bit clearer. 156 00:07:35,589 --> 00:07:38,399 And let's see if we can simplify this further. 157 00:07:38,399 --> 00:07:41,419 And remember, just so you know what I'm doing this whole time. 158 00:07:41,420 --> 00:07:43,770 In the back of my mind I'm trying to get it into the 159 00:07:43,769 --> 00:07:48,169 format that I normally associate with a parabola. 160 00:07:48,170 --> 00:07:49,939 And I'll do it in the corner here, just so you know 161 00:07:49,939 --> 00:07:51,449 where the algebra's going. 162 00:07:51,449 --> 00:07:56,000 I'm trying to get into a format x minus a squared 163 00:07:56,000 --> 00:08:00,870 is equal to y minus b. 164 00:08:00,870 --> 00:08:04,360 Because if we have it in this form, or actually ax. 165 00:08:04,360 --> 00:08:06,580 Let me write that because I went too far to the right. 166 00:08:06,579 --> 00:08:09,909 A times x minus-- well, actually I already used 167 00:08:09,910 --> 00:08:13,260 the A so let me write x minus-- I don't know. 168 00:08:13,259 --> 00:08:19,829 I'll make up x minus-- I'll call that v squared. 169 00:08:19,829 --> 00:08:23,120 I'm picking maybe v for x value of the vertex. 170 00:08:23,120 --> 00:08:25,009 I'm making up variables on the fly. 171 00:08:25,009 --> 00:08:28,930 A times x minus v squared is equal to y minus b. 172 00:08:28,930 --> 00:08:31,000 And you know, the actual letters I chose don't matter. 173 00:08:31,000 --> 00:08:33,860 But this is a general form of a parabola. 174 00:08:33,860 --> 00:08:34,970 And this is where I'm trying to go. 175 00:08:34,970 --> 00:08:37,200 If I can get this thing that we're working on to this 176 00:08:37,200 --> 00:08:39,410 form then we know we're dealing with a parabola. 177 00:08:39,409 --> 00:08:42,129 And then, we can actually relate what we normally 178 00:08:42,129 --> 00:08:44,830 associate with a parabola to these terms up here. 179 00:08:44,830 --> 00:08:46,120 And obviously, these are different letters 180 00:08:46,120 --> 00:08:47,269 than these letters. 181 00:08:47,269 --> 00:08:49,759 And then we can try to figure out-- if we have a parabola, 182 00:08:49,759 --> 00:08:52,590 how do we figure out its focus and is directrix. 183 00:08:52,590 --> 00:08:54,110 But anyway, that was a bit of an aside just so you 184 00:08:54,110 --> 00:08:54,789 know where we're going. 185 00:08:54,789 --> 00:08:57,515 So let's try to simplify this a little bit more. 186 00:08:57,515 --> 00:08:58,856 So we get-- 187 00:08:58,856 --> 00:09:00,350 [PHONE RINGING] 188 00:09:00,350 --> 00:09:03,009 --my phone is ringing. 189 00:09:03,009 --> 00:09:04,200 Let me silent it. 190 00:09:04,200 --> 00:09:10,000 So we get x minus a squared is equal to-- let's see. 191 00:09:10,000 --> 00:09:14,539 If we factor out a 2 and a y we get-- let me 192 00:09:14,539 --> 00:09:15,519 factor out a y first. 193 00:09:15,519 --> 00:09:22,079 We get 2b minus 2k times y. 194 00:09:22,080 --> 00:09:26,259 And then I want to make it minus some constant. 195 00:09:26,259 --> 00:09:27,460 So this is a constant right here. 196 00:09:27,460 --> 00:09:29,650 This is one constant squared plus another constant. 197 00:09:29,649 --> 00:09:36,750 So I could make this equal to minus-- let 198 00:09:36,750 --> 00:09:38,539 me think about this. 199 00:09:38,539 --> 00:09:42,409 This would be minus b squared minus k squared. 200 00:09:42,409 --> 00:09:45,610 If I expand this minus out you would get minus b 201 00:09:45,610 --> 00:09:46,870 squared plus k squared. 202 00:09:46,870 --> 00:09:49,379 So this is the same thing right there. 203 00:09:49,379 --> 00:09:49,870 And let's see. 204 00:09:49,870 --> 00:09:54,840 Can I factor out-- yeah, I can factor out a 2. 205 00:09:54,840 --> 00:10:00,540 The whole thing becomes x minus a squared is equal to 2 times b 206 00:10:00,539 --> 00:10:07,360 minus k times y minus-- and now this is the difference of-- 207 00:10:07,360 --> 00:10:10,680 yeah, this is b plus k times b minus k. 208 00:10:10,679 --> 00:10:15,969 You might want to review factoring polynomials if 209 00:10:15,970 --> 00:10:17,560 that doesn't look familiar. 210 00:10:17,559 --> 00:10:20,779 But this is b plus k times b minus k. 211 00:10:20,779 --> 00:10:23,284 And I want to do that because I saw this b minus k out there so 212 00:10:23,284 --> 00:10:27,230 that looked interesting to get it on both terms right there. 213 00:10:27,230 --> 00:10:27,740 Now let's see. 214 00:10:27,740 --> 00:10:32,060 If we divide everything times-- let's divide everything by 1 215 00:10:32,059 --> 00:10:36,659 over 2 b minus k because I just want a y here, so I have some 216 00:10:36,659 --> 00:10:37,799 coefficient in front of the y. 217 00:10:37,799 --> 00:10:41,329 So let's divide everything by 1 over 2 b minus k. 218 00:10:41,330 --> 00:10:44,420 219 00:10:44,419 --> 00:10:46,429 Let me do it down here so I have some space. 220 00:10:46,429 --> 00:10:57,659 1 over 2 b minus k times x minus a squared is equal to-- 221 00:10:57,659 --> 00:11:01,120 I'm dividing this by 2 b minus k, so that goes away. 222 00:11:01,120 --> 00:11:08,149 So it's y minus-- so if I divide this by 2 b minus k the 223 00:11:08,149 --> 00:11:18,779 b minus k's cancel out and I'm just left with b plus k over 2. 224 00:11:18,779 --> 00:11:22,339 And I think I have gotten it in the form that I wanted. 225 00:11:22,340 --> 00:11:25,480 In this case, the a that I wrote up here is now 226 00:11:25,480 --> 00:11:29,550 1 over 2 b minus k. 227 00:11:29,549 --> 00:11:32,149 This v is this a that I did here. 228 00:11:32,149 --> 00:11:35,399 The y is the y and then my constant term is out here. 229 00:11:35,399 --> 00:11:38,799 So I have hopefully shown to you that the locus of all 230 00:11:38,799 --> 00:11:43,179 points that are equidistant to this point-- which is really 231 00:11:43,179 --> 00:11:44,229 just an arbitrary point. 232 00:11:44,230 --> 00:11:47,110 I said it's the point a, b-- and some line, is 233 00:11:47,110 --> 00:11:48,440 in fact, a parabola. 234 00:11:48,440 --> 00:11:51,960 And that's one of the ways that people define a parabola. 235 00:11:51,960 --> 00:11:54,300 And we'll actually see soon that when you actually change 236 00:11:54,299 --> 00:11:57,929 this relation-- in this case, we found that all of the points 237 00:11:57,929 --> 00:12:00,979 that are equidistant to the focus and the directrix. 238 00:12:00,980 --> 00:12:04,759 If we changed that ratio, if we find all of the points that are 239 00:12:04,759 --> 00:12:08,009 1/2 as far away from the directrix as the focus, we 240 00:12:08,009 --> 00:12:09,830 start getting another conic section. 241 00:12:09,830 --> 00:12:11,410 If we said twice as far we would get another 242 00:12:11,409 --> 00:12:12,059 conic section. 243 00:12:12,059 --> 00:12:15,319 So this is a very interesting way of relating-- sometimes the 244 00:12:15,320 --> 00:12:17,850 conic sections in the first video I showed how they're all 245 00:12:17,850 --> 00:12:19,970 related to cutting the three-dimensional cone. 246 00:12:19,970 --> 00:12:22,610 But they're also related in this way and eventually I want 247 00:12:22,610 --> 00:12:25,129 to relate this to the three-dimensional cone so you 248 00:12:25,129 --> 00:12:26,789 can see how it all fits together. 249 00:12:26,789 --> 00:12:29,809 Which is always the fun thing about mathematics. 250 00:12:29,809 --> 00:12:33,789 So this so far, all we've shown to you is if we do take the 251 00:12:33,789 --> 00:12:36,779 locus of all points that are equidistant to a point and a 252 00:12:36,779 --> 00:12:38,769 directrix that it is a parabola. 253 00:12:38,769 --> 00:12:40,569 Now, the interesting thing to do is let's 254 00:12:40,570 --> 00:12:43,830 say I have a parabola. 255 00:12:43,830 --> 00:12:46,490 Let me give a general form. 256 00:12:46,490 --> 00:12:48,810 And I'll try to use different letters than I used up here. 257 00:12:48,809 --> 00:12:54,051 So let's say I have a parabola y minus-- 258 00:12:54,052 --> 00:12:56,920 let's call it y sub 1. 259 00:12:56,919 --> 00:13:01,069 Where it's just a particular point on the parabola. 260 00:13:01,070 --> 00:13:05,090 Y minus y sub 1 or you could call it some constant-- is 261 00:13:05,090 --> 00:13:09,585 equal to-- let's call it, I want to use a capital A just 262 00:13:09,585 --> 00:13:12,090 because that tends to be-- I'll use a capital A and just 263 00:13:12,090 --> 00:13:14,340 know that it's different than this lowercase A. 264 00:13:14,340 --> 00:13:18,960 Some capital A times x minus x sub 1. 265 00:13:18,960 --> 00:13:19,200 squared. 266 00:13:19,200 --> 00:13:22,140 Whenever you see a y sub 1 or an x sub 1, that means you're 267 00:13:22,139 --> 00:13:23,769 actually dealing with a constant term. 268 00:13:23,769 --> 00:13:26,559 If you see just an x or y that generally means that you're 269 00:13:26,559 --> 00:13:27,769 dealing with a variable term. 270 00:13:27,769 --> 00:13:28,569 So these are constants. 271 00:13:28,570 --> 00:13:30,240 I could have put letters there. 272 00:13:30,240 --> 00:13:32,000 I could have put a and b there, but then that would've 273 00:13:32,000 --> 00:13:33,070 gotten confused with that. 274 00:13:33,070 --> 00:13:35,970 But let's see if we can relate these letters because this is 275 00:13:35,970 --> 00:13:37,269 something that we normally see. 276 00:13:37,269 --> 00:13:40,689 And then, we want to find the focus or the directrix 277 00:13:40,690 --> 00:13:41,870 of a parabola like this. 278 00:13:41,870 --> 00:13:44,950 How can we relate these to these values right here? 279 00:13:44,950 --> 00:13:48,860 How does k and a and b relate to these right there? 280 00:13:48,860 --> 00:13:49,810 So let's see if we can set that up. 281 00:13:49,809 --> 00:13:54,599 So if we just pattern match that is A. 282 00:13:54,600 --> 00:13:58,250 If we say x sub 1 is lowercase a, actually that's a straight 283 00:13:58,250 --> 00:14:00,769 up pattern match, so we can already write that on the side. 284 00:14:00,769 --> 00:14:03,829 x sub 1 is equal to a. 285 00:14:03,830 --> 00:14:06,210 So whatever x value I have here, this is also the x 286 00:14:06,210 --> 00:14:07,750 value of the focus point. 287 00:14:07,750 --> 00:14:10,210 Which makes sense because in this case, we already learned 288 00:14:10,210 --> 00:14:11,235 this in previous video. 289 00:14:11,235 --> 00:14:15,659 But we learned that the vertex of this parabola is the 290 00:14:15,659 --> 00:14:19,159 point x sub 1 comma y sub 1. 291 00:14:19,159 --> 00:14:20,370 Anyway, I don't want to confuse you. 292 00:14:20,370 --> 00:14:21,690 Actually, you know what I'm going to do? 293 00:14:21,690 --> 00:14:24,980 I don't want to go too far off into this topic, and I think 294 00:14:24,980 --> 00:14:26,519 this video has already gotten long enough. 295 00:14:26,519 --> 00:14:28,110 I will continue this in the next video. 296 00:14:28,110 --> 00:14:29,611 See you soon. 297 00:14:29,611 --> 00:14:30,322