Math, asked by TbiaSupreme, 1 year ago

If A, B and C are interior angles of triangle ABC, then show that sin (B + C)/2 = cos A/2

Answers

Answered by mysticd
10
Hi ,


It is given that ,

A , B and C are interior angles of triangle

ABC ,

A + B + C = 180°

B + C = 180° - A

( B + C )/2 = 180°/2 - A/2

( B + C ) / 2 = 90° - A/2

Now ,

sin( B + C )/2 = Sin ( 90° - A/2 )

sin ( B + C )/2 = cos A/2

Hence proved.

: )
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