Упростите: (sina+cosa)^2-(1+sin2a)

Question

Упростите: (sina+cosa)^2-(1+sin2a)

Answer 1

 (sina+cosa)²-(1+sin2a)=sin²a+2sinacosa+cos²a-1-sin2a=
=(sin²a+cos²a)-1+sin2a-sin2a=1-1=0

Answer 2

Sin^2α+2sinα*cosα+cos^2α-1-2sinα*cosα=1+2sinα*cosα-1-2sinα*cosα=0