(adsbygoogle = window.adsbygoogle || []).push({}); [SOLVED] Trig Identities and Double Angle Formulas

1. The problem statement, all variables and given/known data

If tan(a) = 1/5 and tan(b) = 1/239, find tan(4a - b)

2. Relevant equations

tan2x = 2tanx/1-tan^2x

tan(x-y) = tanx - tany/ 1 +tanx tany

3. The attempt at a solution

tan (4a - b) = (tan4a - tanb)/(1 + tan4a tanb)

= ((2tan2a/1-tan^2 2a) - tanb)/ (1-(2tan^2 2a/1-tan^2 2a)tanb)

= ((2tan2(1/5)/1-tan^2 2(1/5)) - tan(1/239)) / (1 - (2tan^2 2(1/5))tan(1/239))

= ((2tan(2/5))/1-tan^2 (2/5)) - tan(1/239)) / (1 - 2tan^2 (2/5)tan(1/239))

After this I get stuck. Please someone help. I need this really quick.

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# Homework Help: Trig Identities and Double Angle Formulas

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