Given that cosx=p find an expression, in terms of p, for tan2x?

2 Answers
Oct 12, 2015

tan2x=1p2p2

Explanation:

If cos x =p, sinx=1p2

tan x = 1p2p

tan2x=1p2p2

Oct 12, 2015

tan2x=1p2p2=1p21

Explanation:

If cosx=p, then

cos2x=p2.

By Pythagoras, sin2x+cos2x=1, so:

sin2x=1cos2x=1p2

Now tanx=sinxcosx, so

tan2x=sin2xcos2x=1p2p2=1p21