Question

Evaluate sin 60°cos 30° + sin30°cos 60°. What is the value of sin(60° + 30°). What can you conclude?

Answer 1

Let plug A = 60° and B= 30°

sin A.cos B + cos A. sin B

which corresponds to the addition formula

sin(A+B)

sin(60° + 30°) = sin 90°

which gives the unit circle value 1

hence the value ofthe expression

sin60°.cos30° + cos 60°.sin 30° = 1

Hence we can conclude that we can either plug in the unit circle values to solve or just use the addition or subtraction identities