(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

In a triangle ABC, a=6 b=3 cos(A-B)=4/5. Find the angle C.

2. Relevant equations

3. The attempt at a solution

here we need to find tan(A-B/2)

I used the formula tan2x=2tanx/(1/tan^2x)

and got 2 values of tan(A-B/2) as -3 and 1/3

On what explanation do I reject one of them?

-90<A-B/2 <90

so tanA-B/2 can be both positive and negative.

Please explain in detail

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# Homework Help: Napier's analogy

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