triangles

Asked by  | 13th Feb, 2009, 10:25: PM

Expert Answer:

A,B and C are the interior angles of a triangle.

So,

 A +  B+  C= 180

Now,

sin[( B+C)/2]=sin [(180-A)/2]

=sin[90-(A/2)]

=cos(A/2)

Answered by  | 14th Feb, 2009, 05:33: PM

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