PLEASE HELP ME WITH THIS TRIGONOMETRY QUESTION!!?

Question

Edit
Express each of the following in terms of another angle between 0 degrees and 180 degrees
a. sin 50 degrees
b. sin 150 degrees
c. cos 45 degrees
d. cos 120 degrees
Update: we have not yet learnt it in class i'm trying to analysis it but its not making senses, if you know how to solve it please show me the steps, i'm eager to learn!

Answer 1

recall that
sin(180-x) = sin(x)
cos(180-x) = -cos(x)

Using those two facts, you can replace each angle by its supplement.

Now, if you want to get fancy,

sin(90+x) = cos(x)
cos(90+x) = -sin(x)

As Reiny suggested, start by drawing triangles in the "standard position." goggle that if you don't understand the idea.