" 11."b sin B-c sin C=a sin(B-C)

a sin A-b sin B=c sin(A-B)

a sin A-b sin B=c sin(A-B)

a sin A-b sin B=c sin(A-B)

Simplify: (sin(A - B))/(sin A sin B) + (sin(B - C))/(sin B sin C) + (sin (C - A))/(sin C sin A)

(sin(A - B))/(sin A sin B) + (sin(B - C))/(sin B sin C) + (sin (C - A))/(sin C sin A)=0

Prove that (sin (A - B))/( sin A sin B ) + ( sin (B -C))/( sin B sin C ) + (sin (C - A))/( sin C sin A) =0

Show that: sin A + sin B +sin C - sin(A+B+C)=4 sin ((A+B)/2)sin ((B+C)/2)sin ((C+A)/2)

If : A+B+C=pi, "then" : sin 2A + sin 2 B - sin 2 C= A) 4 sin A * cos B * cos C B) 4 sin B * sin C * cos A C) 4 sin C * cos A * cos B D) 4 sin A * sin B * sin C

If A+B+C= pi and (sin 2 A + sin 2B + sin 2 C)/(sin A + sin B + sin C ) = lamda sin ((A)/(2)) sin ((B)/(2)) sin ((C )/(2)) , then the value of lamda must be