Q5 of 46 Page 288

If A, B and C are interior angles of a triangle ABC, then show that

If A, B and C are interior angles of ∆ABC, then we can say that

A + B + C = 180° (by angle sum property of a triangle)


⇒ A + B = 180° - C


Take LHS:



⇒


⇒


[∵, tan (90° - θ) = cot θ, where θ = C/2 here]


Hence, .


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