sin x = sin(π-x)=-sin(π+x)=-sin(-x)

cos x =-cos(π-x)=-cos(π+x)= cos(-x)

tan x =-tan(π-x)= tan(π+x)=-tan(-x)

sin x=cos (90 -x)

cos x=sin(90 -x)

sin(90 +x)=cos x

cos(90 +x)=-sin x

sin2x=2sinx cosx

cos2x= 1-2sin？ x=- 1+2cos？ x=cos？ x-sin？ x

tan2x=(2tanx)/( 1-tan？ x)

Sin? x=( 1-cos2x)/2

Because? x=( 1+cos2x)/2

Tan? x =( 1-cos2x)/( 1+cos2x)

Can't play it all! What a waste of time! ! !