Question

Show the steps to simplfiying sin(a-b)sin(a+b)=(cosb)^2-(cosa)^2

Answer 1

This question is hard. D:

Answer 2

If you get bored of this question I got 2 others.

Answer 3

sin(a-b)sin(a+b)=
[sin(a)cos(b)-cos(a)sin(b)][sin(a)cos(b)+cos(a)sin(b)]=
sin^2(a)cos^2(b)-cos^2(a)sin^2(b)=
(1-cos^2a)cos^2b-cos^2a(1-cos^2b)=
cos^2b-cos^2acos^2b-cos^2a+cos^2acos^2b=
cos^2b-cos^2a

Answer 4

ohhhh, see i was going on the same path as you. But somehow I didn't follow through enough like you.