00:01
Okay, you are given that sine of u is equal to 1213th, cosine of v is negative for fifths, and you are in quadrant two.
00:17
In quadrant two, so this is quadrant two, x is negative, so cosine of theta is negative, sine of theta is positive.
00:31
So that's to keep in mind.
00:34
We need to find cosine of u minus v.
00:38
This is cosine of u, cosine of v, plus sign of u, sign of v.
00:47
This is an identity.
00:49
So if sine of u is 1213th, then let's create a triangle.
00:59
So this is angle u and another triangle for the other one.
01:04
For angle v.
01:08
Angle you.
01:10
Sign is opposite over hypotenuse.
01:14
Here, cosine is adjacent over hypotenuse.
01:20
This one is a 3, 4, 5 right triangle.
01:24
It's a very common right triangle.
01:26
This one we're going to have to solve out.
01:28
13 squared is equal to a squared plus 12 squared.
01:34
So 13 squared...
