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+1 vote
41.3k views
in Co-ordinate geometry by (63.5k points)

If in a triangle ABC 2cosA/a + cosB/b + 2cosC/c = a/bc + b/ca  then the value of the angle A is …….. degree. 

1 Answer

+3 votes
by (64.8k points)
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Best answer

Given, 2cosA/a + cosB/b + 2cosC/c = a/bc + b/ca ...(i)

We know that, cos A = (b2 + c2 - a2)/2bc

cosB = (c2 + a2 - b2)/2ac

and cosC = (a2 + b2 - c2)/2ab

On putting these values in Eq. (i), we get

⇒ b2 + c2 = a

Hence, the angle A is 90º 

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