Q. 6

# Mark the Correct alternative in the following:

In a ∆ABC, if (c + a + b) (a + b – c) = ab, then the measure of angle C is

A.

B.

C.

D.

Answer :

ac + bc – c^{2} + a^{2} + ab - ac + ab + b^{2} - bc - ab=0

– c^{2} + a^{2} + ab + b^{2} =0

a^{2} + b^{2} – c^{2} = - ab

By Cosine law,

Option C

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