Thread: Using Trigonometric Identity

a) Find the exact value of sin 135 by using sin (180 – 45)

b) Find the exact value of sin 225 by using sin (270 – 45)
b) Use the value of sin 225 found in b to find sin (–15) by using sin (225 – 240)

Recall

so

Originally Posted by pickslides

Recall

so

but how i can solve part c of the question

Are expected to solve the problem by using

sin(A-B) = sinAcosB - cosAsinB ?