# Math Help - simplifying trignometry in calculus

1. ## simplifying trignometry in calculus

How does this simplify to sin3x:

sinxcos2x + sin2xcosx = sin3x

this is part of parametric equations ch10 in my Calculus textbook. I am not sure if they used a trig identity or pure algebra.

thank you

2. Are you asking a question different to sinAcosB+cosAsinB=sin(A+B) ?

3. Thanks for the help. You are right about that identity.

I knew the Calculus but it is only the trig and algebra which costs me points on the Calculus exam.

Thanks again. So How do I give you exp points for helping me out so the green balls will

4. Here's a reasonable list of trig identities.
I don't know about the green dots either!
you're welcome.