Question

Prove that :

( Sin A + B ) = Sin A Cos B + Sin B Cos A.

Answer 1

$hi$
Here ..

L.H.S :
Sin ( A + B ) = SinA + SinB
we know that ,

SinB = Cos(90 - B)

So..

SinA + Cos(90 - B)

SinA + Cos90 - CosB

SinA + 0 - CosB

SinA - CosB

L.H.S = SinA - CosB

Now ,
Using Identity
SinA = Cos (90 - A)
CosA =Sin(90 - A)

Try to solve it
Remember the R.H.S
also must be SinA - CosB

$hope \: \: this \: \: helps.$