Search
Ask a question
0

show that cos(A-B) - cos(A+B) = 2sinA sinB

Anybody have  an idea how to solve that question... think needs to simplify first and use identities to solve.. but cant even start it..

 

please any help is welcome..

1 Answer by Expert Tutors

Tutors, sign in to answer this question.
Kevin S. |
5.0 5.0 (4 lesson ratings) (4)
0

cos (A - B) = cos A cos B + sin A sin B

cos (A + B) = cos A cos B - sin A sin B

so 

cos (A - B) - cos (A + B) = [cos A cos B + sin A sin B] - [cos A cos B - sin A sin B]

Simplify and solve.