Question

Show that cos square (45degree-theta)cos square (45degree+theta)=1

Answer 1

Answer:-

We know, 2cos^2 x=1+cos2x.

∴cos^2x= 1+cos^2x

=> cos^2 (45°+θ) = 1+cos(90°+θ)/2 = 1−sinθ/2

=> cos^2(45°−θ) = 1+cos(90°−θ)/2 = 1+sinθ/2

=> 1-sinθ/2 + 1+sinθ/2

=> 1