Given: A. sin(x)

B. cos(x)

C. cos(y)

D. sin(y)

Use the drop-down menus in the derivation of the sine sum identity:

sin(x + y)

= cos (StartFraction pi Over 2 EndFraction minus (x + y))

= Cosine ((StartFraction pi over 2 EndFraction minus x) minus y)

= Cosine (StartFraction pi Over 2 EndFraction minus x)
A
+ Sine (StartFraction pi Over 2 EndFraction minus x)
A

sin(x)cos(y) + cos(x)sin(y)