In triangle ABC, (b+c)cos A + (c+a) cos B + (a+b) cos C = [MP PET 1985]

0.0

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a + b + c

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2(a+b+c)

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Solution

The correct option is B 1
(b+c) cos A + (c + a)cos B + (a+b) cos C = a + b + c
From expanding and collecting terms using projection rule, a = b cos C + c cos B etc.

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