Question

(√3)cosa-2cos(a-30˚)+sina

Answer 1

√3 Cosα - 2(CosαCos30° + SinαSin30°) + Sinα =
=√3Cosα-2( Cosα*√3/2 + Sinα*1/2) +Sinα = 
= √3Cosα - √3Cosα - Sinα + Sinα = 0