Question

The expression
cos? (A - B) + cos2 B – 2 cos(A - B).
cos A cos B is independent of what angle ?​

Answer 1

Answer:

dependent on A

Step-by-step explanation:

cos

2

(A−B)+cos

2

B−2cos(A−B)cosAcosB

cos(A−B)[cos(A−B)−2cosAcosB]+cos

2

B

=cos(A−B)[sinAsinB−cosAcosB]+cos

2

B

=−cos(A−B)cos(A+B)+cos

2

B

=−[

2

cos2A+cos2B

]+cos

2

B

=−[

2

2(cos

2

A+cos

2

B)−2

]+cos

2

B

=−cos

2

A−cos

2

B+1+cos

2

B

=1−cos

2

A

=sin

2

A

Expression is only dependent of A.

Hope you understand my answer.