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If semiperimeter of a triangle is 15, ...

If semiperimeter of a triangle is 15, then the value of `(b+c)cos(B+C)+(c+a)cos(C+A)+(a+b)cos(A+B)` is equal to :
(where symbols used have usual meanings)

A

-60

B

-15

C

-30

D

can not be determined

Text Solution

Verified by Experts

The correct Answer is:
C
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