Trigonometric identities

Prove the following identity:
(1-cosx) / (1+cosx)= tan^2(x/2)

Thanks in advance :smile:

(edited 7 years ago)

Know any double angle formulae for cosine to get rid of the +1 and -1 in the numerator and denominator?

yes, but i don't understand how they fit in this identity

yes, but i don't understand how they fit in this identity

\cos x \equiv 2\cos^2 (x/2)-1\equiv 1-2\sin^2 (x/2)

.
Use each one of these identities on numerator or denominator to get rid of the constants.

Got it! Thank you so much :biggrin:

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