You cant solve this if it doesnt say what the expression totals up to, sorry!
Answer:
C
Step-by-step explanation:
It goes up one and over two and has a y-intercept of 3
Cos (a-b) = cos(a)cos(b) + sin(a)sin(b)
cos (a+b) = cos(a)cos(b) - sin(a)sin(b)
so, cos(a-b) - cos(a+b) =
=cos(a)cos(b) + sin(a)sin(b) - [cos(a)cos(b) - sin(a)sin(b)]
=2sin(a)sin(b)