Home » If A, B, C are the Interior Angles of △ABC, Prove that tan [(B + C)/2] = cot A/2

If A, B, C are the Interior Angles of △ABC, Prove that tan [(B + C)/2] = cot A/2

by Sana Imran

Question: If A, B, C are the Interior Angles of △ABC, Prove that tan [(B + C)/2] = cot A/2

Answer:

Here, B + C  = 180˚ – A

(B + C)/2 = 90˚ – A/2

Taking tan on both sides, we get

tan (B + C)/2 = tan(90˚ – A/2)

= cot A/2

Hence  proved tan [(B + C)/2] = cot A/2

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