Evaluate `cos^2A.cos^2B-sin^2A.sin^2B`

The value of sin^2 A cos^2 B + cos^2 A cos^2 B+sin^2 A sin^2 B + cos^2A sin^2B is ……..

Find the value of (cos2B-cos 2A)/(sin2A+sin2B) :

cos(A+B)*cos(A-B)= (a) sin^2A-cos^2B (b) cos^2A-sin^2B (c) sin^2A-sin^2B (d) cos^2A-cos^2B

Prove that (sin^Acos^B-cos^2Asin^2B)=(sin^2A-sin^2B)

sin^(2)A cos^(2)B-cos^(2)A sin^(2)B=sin^(2)A-sin^(2)B

Prove the following identities: tan^(2)A-tan^(2)B=(cos^(2)B-cos^(2)A)/(cos^(2)B cos^(2)A)=(sin^(2)A-sin^(2)B)/(cos^(2)A cos^(2)B)(sin A-sin B)/(cos A+cos B)+(cos A-cos B)/(sin A+sin B)=0

If (cos^(4)A)/(cos^(2)B)+(sin^(4)A)/(sin^(2)B)=1 then prove that (i)sin^(2)A+sin^(2)B=2sin^(2)A sin^(2)B(ii)(cos^(4)B)/(cos^(2)A)+(sin^(4)B)/(sin^(2)A)=1

to prove that (cos A-cos B)^(2)+(sin A-sin B)^(2)=4sin^(2)((A-B)/(2))

Prove that (cos A-cos B)^(2)+(sin A-sin B)^(2)=4sin^(2)((A-B)/(2))

(i) (1)/(sin^(2)a)-(1)/(sin^(2)B)=(cos^(2) a-cos^(2) B)/(sin^(2)a*sin^(2) B)