" (b) "cos^(2)((pi)/(4)-theta)-sin^(2)((pi)/(4)-theta)=sin2 theta

Prove that: cos^(2)((pi)/(4)-theta)-sin^(2)((pi)/(4)-theta)=s in2 theta

(1-tan^(2)((pi)/(4)-theta))/(1+tan^(2)((pi)/(4)-theta))=sin2 theta

Prove that: cos^2(pi/4-theta)-sin^2(pi/4-theta)=sin2theta

Prove that cos^2(pi/4-theta)-sin^2(pi/4-theta)=sin 2theta

2cos((pi)/(2)-theta)+3sin((pi)/(2)+theta)-(3sin theta+2cos theta)=

Prove that 4sin theta sin((pi)/(3)+theta)sin((2 pi)/(3)+theta)=sin3 theta

If : sin^(2) ((pi)/(4) + (theta)/(2)) - cos^(2) ((pi)/(4) + (theta)/(2))= A) sin theta B) cos theta C) sin 2 theta D) cos 2 theta

Prove that sin ^(2) ((pi)/(8) + (theta)/(2)) - sin ^(2) ((pi)/(8) - (theta)/(2)) = sin ""(pi)/(4) sin theta.

I : If sin((pi)/(4)cot theta)=cos ((pi)/(4)tan theta) then theta = n pi+pi//4, n in Z II : If tan ((pi)/(2)sin theta)=cot((pi)/(2)cos theta) then sin (theta + (pi)/(4))= pm (1)/(sqrt(2))

Prove that : cos (pi/4- theta)cos (pi/4-phi)-sin(pi/4-theta) sin (pi/4-phi)= sin (theta+phi) .