Prove sin(b+c)/2=cos a/2

1.	Prove sin(b+c)/2=cos a/2
Answer» let a,b and c are the angles of one triangleTherefore, a+b+c=180°(A.S.P)now b+c=180°-a___(i)Divide (i) by 2 on both sidesb+c/2=90°-a/2Now, sin (b+c/2) =sin(90-a/2)Therefore, sin(b+c/2)=cos a/2 (because sin90-thetha = cos thetha)HENCE PROVED

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