Cos(pi+2a)+sin(pi+2a)*tg(pi/2+a)

Question

Cos(pi+2a)+sin(pi+2a)*tg(pi/2+a)

Answer 1

-cos2a+sin2a*ctga=-cos2a+2cos^2a=-cos^2a+sin^2a+2cos^2a=sin^2a+cos^2a=1