Question

If A+B+C = 180°,
prove that
sinA+sin(B-C) = 2sinBsinC

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So important....

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Answer 1

HELLO........FRIEND!!

THE ANSWER IS HERE,

A+B+C= 180.

A =180-(B+C).

join Sin on both sides.

=> SinA=Sin (180-(B+C)

=> SinA=Sin (B+C).

Given that,

=> SinA+Sin (B-C)

=> Sin (B+C)+Sin (B-C).

We know the formula,

Sin (B+C) = SinB.CosC+CosB. SinC
Sin (B-C) = SinB. CosC -CosB. SinC.

By adding we get,

=> SinB.CosC +CosB. SinC +SinB. CosC -CosB. SinC.

=> 2SinB.CosC.

So,

=> SinA +Sin (B-C) = 2SinB.CosC.

I think My answer will help u.

Answer 2

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