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If tan(A +B) = And tan(A -B) = y, find the values of tan 2A And tan 2B. |
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Answer» Given tan(A +B) = x And tan(A –B) = y Consider tan 2A = tan(A +A) = tan(A +B +A –B) We know that tan(A+B) = \(\frac{tanA+tanB}{1-tanAtanB}\) ⇒ tan(A + B + A - B) = \(\frac{tan(A+B)+tan(A-B)}{1-tan(A+B)tan(A-B)}\) = \(\frac{x+y}{1-xy}\) Consider tan 2B = tan(B +B) = tan(B +A +B –A) = \(\frac{tan(B+A)+tan(B-A)}{1-tan(B+A)tan(B-A)}\) We know that tan(-θ) = - tan θ = \(\frac{tan(A+B)-tan(A-B)}{1+tan(A+B)tan(A-B)}\) = \(\frac{x-y}{1+xy}\) |
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