Math help : how do I solve out sin (u+v) + sin(u-v)?

Try looking at the identities: http://en.wikipedia.org/wiki/Trigonometric_functions#Identities

Check your algebra. When you substitute into sin(u+v) + sin(u – v), the sin u * cos v terms add together and the cos u * sin v terms cancel.

http://answers.yahoo.com/question/index?qid=20110628171913AAdSzKJ

i’ll spare you the www.lmgtfy.com link

@nailpolishfanatic You wrote…

Simplify : Sin ( u + v) + Sin (u – v)
Sin ( u + v ) = sin u * cos v + cos u * sin v
Sin ( u – v ) = sin u * cos v – cos u * sin v

…which is totally right. Then you made mistakes in the lines after that. It’s probably easier than you think.
If you simplify the notation by substituting x = sin u cos v and y = cos u sin v
then your own formulas read:
Sin ( u + v ) = x + y
Sin ( u – v ) = x – y

So the sum of these quantities on the left yields, on the right, x+y+x-y = 2x
and 2x is shorthand for 2 sin u cos v.

Man, I haven’t done someone else’s homework in soooo long.