Question

TRIG Identities, Gr. 12:
Prove:
cot4x=1-tan^2x/2tan2x

Answer 1

just apply the double-angle formula for tan(2x) and take the reciprocal

Answer 2

okay, thank you, would that still apply if it was cot4x=1-tan^2(2x)/2tan2x? because ive got the right side for this one but the cot4x is throwing me off, how would you solve that side?

Answer 3

you are exactly right

tan(4x) = 2tan2x/(1-tan^2(2x))
so, cot(4x) is the reciprocal, as needed.