Question

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

Answer 1

Answer:

..... .................. .

Answer 2

Answer:

Taking RHS:

cos(A−B)[cos(A−B)−2cosA.cosB]+cos

2

B

=cos(A−B)[cosA.cosB+sinA.sinB−2cosA.cosB]+cos

2

B

=−cos(A−B).cos(A+B)+cos

2

B

=cos

2

B−

2

2cos(A−B)cos(A+B)

=

2

1

[2cos

2

B−cos2A−cos2B]

=

2

1

[2sin

2

A]=sin

2

A