cos(3pi/2+a)sin(p+a)-tg(pi\2+a)tg(2pi+a)

Question

cos(3pi/2+a)sin(p+a)-tg(pi\2+a)tg(2pi+a)

Answer 1

cos(3pi/2+a)sin(p+a)-tg(pi\2+a)tg(2pi+a)=>

cos(3pi/2+a)=sin a

sin(p+a)=-sin a

tg(pi\2+a)=-ctg a

tg(2pi+a)=tg a

(sin a)(-sin a)-(-ctg a)(tg a)= -sin^{2}a +1=cos^{2}a