A, B, and C are 3 angles in triangle ABC then sin(A+B)=?

(a) sinA (b)sinB (c)sinC (d)cosC (e) -sin(A+B)

1 Answer
Jul 12, 2018

sin(A+B)=sinC

Explanation:

We know that , in triangleABC

A+B+C=pi

=>A+B=pi-C

So,

sin(A+B)=sin(pi-C)toII^(nd)Quadrant=>sinC >0

=>sin(A+B)=sinC

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Please Carefully, see the image given below to understand the quadrant.

Compare with color(red)( :pi-theta toII^(nd)Quadrant.

enter image source here