Search 83,182 tutors
FIND TUTORS
Ask a question
0 0

How to prove this identity

Tutors, please sign in to answer this question.

1 Answer

tan3x - tan2x- tanx=tan(2x+x)-tan2x-tanx=(tan2x+tanx)/(1-tan2xtanx)-(tan2x+tanx)
=(tan2x+tanx)(1/(1-tan2xtanx)-1)=(tan2x+tanx)(1-(1-tan2xtanx))/(1-tan2xtanx)
=(tan2x+tanx)(tan2xtanx/(1-tan2xtanx)=[(tan2x+tanx)/(1-tan2xtanx)]tan2xtanx=tan3xtan2xtanx