Sin(π/2+α)-cos(π+α)+tg(π+α)+ctg(3π/2+α)=cos2α

Question

Sin(π/2+α)-cos(π+α)+tg(π+α)+ctg(3π/2+α)=cos2α

Answer 1

Sin(pi/2 + a) - cos(pi + a)+tg(pi + a)+ctg( 3pi/2  + a) = - cos a + cos a+ tg a - tg a = 0