= sin^2(180-a) + tan^2(180+a)tan^2(270+a) + sin(90+a)cos(a-360)= sin^2(180-a) + tan^2(180+a)tan^2(270+a) + sin(90+a)cos(a)= sin^2(a) + tan^2(a)cot^2(a) + cos(a)sin(a)= sin^2(a) + (sin^2(a)/cos^2(a))(cos^2(a)/sin^2(a)) + 2cos(a)sin(a)= sin^2(a) + sin^2(a) + 2cos(a)sin(a)= 2sin^2(a) + 2cos(a)sin(a)= 2(sin^2(a) + cos(a)sin(a))= 2sin(a)
= sin^2(180-a) + tan^2(180+a)tan^2(270+a) + sin(90+a)cos(a-360)
= sin^2(180-a) + tan^2(180+a)tan^2(270+a) + sin(90+a)cos(a)
= sin^2(a) + tan^2(a)cot^2(a) + cos(a)sin(a)
= sin^2(a) + (sin^2(a)/cos^2(a))(cos^2(a)/sin^2(a)) + 2cos(a)sin(a)
= sin^2(a) + sin^2(a) + 2cos(a)sin(a)
= 2sin^2(a) + 2cos(a)sin(a)
= 2(sin^2(a) + cos(a)sin(a))
= 2sin(a)