Question

prove that
sin(50+A)cos(40-B)+cos(50+A)sin(40-b)=cos(A-B)​

Answer 1

Answer:

sin(90-50) sin 40 + cos (90-50) cos 40

sin40 sin40 + cos40 cos40

sin^2 40 + cos^2 40

(since sin @ + cos@ =1)

so sin^2 40 + cos^2 40 = 1

Step-by-step explanation: