00:01
Okay, so we're given that the cosine of alpha is root 17 over 9, and that alpha is between 0 and pi over 2.
00:06
So i'm going to model this alpha in the first quadrant, and it's going to look like this ability here.
00:12
It'll be root 17 and 9.
00:14
The first sign of beta is negative 3 eighths, and it's in quadrant 3, it says.
00:18
So it's going to look like this.
00:19
So it'll be opposite over hypotenuse, so it'll be 3 and 8 like that.
00:24
So what i need to do is i need to find my missing sides here to help with the next section of the sine of alpha plus beta.
00:30
Because if i want to find sine of alpha plus beta, that is sine of alpha times the cosine of beta plus the cosine of alpha times the sine of beta.
00:42
So here, like this y value i'll call it, y squared is equal to 9 squared minus root 17 squared.
00:51
So y is going to come out to 8 here when i do the square root of both sides of this.
00:59
This...