Guest

prove that (cos5x+cos4x)/2cos3x-1 =cosx+cos2x

prove that (cos5x+cos4x)/2cos3x-1 =cosx+cos2x

Grade:11

1 Answers

Rinkoo Gupta
askIITians Faculty 81 Points
10 years ago
To prove (cos5x+cos4x)/2cos3x-1 =cosx+cos2x
I.e. To prove cos5x+cos4x=(2cos3x-1)(cosx+cos2x)
RHS=(2cos3x-1)(cosx+cos2x)
=2cos3xcosx+2cos3xcos2x-cosx-cos2x
=cos4x+cos2x+cos5x+cosx-cosx-cos2x
=cos4x+cos5x=LHS
Thanks & Regards
Rinkoo Gupta
askIITians Faculty

Think You Can Provide A Better Answer ?

ASK QUESTION

Get your questions answered by the expert for free