Welcome :: Homework Help and Answers :: Mathskey.com
Welcome to Mathskey.com Question & Answers Community. Ask any math/science homework question and receive answers from other members of the community.

13,459 questions

17,854 answers


790,609 users

Express 2cos5xcos2x as a sum containing only sines or cosines?

0 votes
please help!
asked Mar 6, 2013 in TRIGONOMETRY by anonymous Apprentice

1 Answer

0 votes


Sum of the cosine rule

Cos(A+B)+Cos(A-B) = 2CosACosB

Substitute 5x for A and 2x for B in above formulae


=cos7x+cos3x                          (Simplify)

Simplified expression is cos7x+cos3x


answered Mar 6, 2013 by bradely Mentor

Related questions