This should be the identity that will solve it..
Angles for sum and difference identities?
how to find the angle of the sum and difference identities
for example sin 15 =(60-45) form where did the 60 and 45 come from and how did you get them in order to solve the problem
Why can't we use instead of 60 -45 >>>>>>10 +5?
The reason we want to use 60 and 45 is because they are special angles which we can easily find the trig functions for without using a calculator.
From the unit circle, you should know that:
Now just substitute these values into your angle difference identity: