00:01
We have some information about two triangles on x and y coordinates, where o is at 0 ,0.
00:09
So the first thing they tell us is that the equation of bc is y equals 4.
00:14
So that means that this distance here is 4, and that point c is located at 0 .4.
00:25
Okay, now they tell us that the x coordinate of point b is a.
00:31
So right here point b the x coordinate is a and we already know that the height of that is four.
00:42
So point b has to be at a four.
00:47
So then the gradient of ob so right here that's slope.
00:54
So think of gradient as slope and the slope of that line is going to be four over a because it's up four and then over a.
01:13
So this distance here is a.
01:18
The gradient of ab, because it's perpendicular to ob, you're going to use the opposite reciprocal.
01:28
So it's going to be a over four and then make it negative because they're perpendicular.
01:37
All right.
01:37
Now to show that the equation, of this line is this.
01:46
We have point b is at a4 and we have the slope of a b...