Question

If A = 60° and B = 30°, verify that: sin (A + B) = sin A cos B + cos A sin B.

Answer 1

LHS ⇒ sin (A + B) = sin (60° + 30°)

= Sin 90°

= 1

RHS ⇒ sin A cos B + cos A sin B

= sin 60° cos 30° + cos 60° sin 30°

= `sqrt3/2 xx sqrt3/2 + 1/2 xx 1/2`

= `3/4 + 1/4`

= `4/4`

= 1