Question

Need Help!

Answer 1

@mathmate

Answer 2

Hint:
sin(x+y)=sin(x)cos(y)+cos(x)sin(y)
sin(x-y)=sin(x)cos(y)-cos(x)sin(y)
For additional information:
cos(x+y)=cos(x)cos(y)-sin(x)sin(y)
cos(x-y)=cos(x)cos(y)+sin(x)sin(y).
There should be sufficient information to figure out if the statement is true/false