If A,B, and C are angles in a triangle prove that sin B=sin(A+C).
Follow Math Help Forum on Facebook and Google+
If A, B, and C are angles in a triangle, then A + B + C = 180 deg
So sin(B) = sin(180 - (A + C)) = sin(180)cos(A + C) - cos(180)sin(A + C) (Double-Angle formula)
= sin(A + C). (sin(180) = 0 & cos(180) = -1)
View Tag Cloud