# Simple Derivative Problem

Find the derivative of (4995)/(1+.12cosθ), when θ = 120°

My attempt:

d/dx [4995/(1+.12cosθ) = (4995)(-1)(1+.12cosθ)-2(.12)(-sinθ)

Letting θ = 120°...

= (4995)(-1)(1+.12(-1/2))-2(.12)(-$\sqrt{3}$/2)

My calculator says that is about 587.478

But it's supposed to be about 10.253

I just started calculus, so I'm probably making some really basic mistake.

Related Calculus and Beyond Homework Help News on Phys.org
Bacle2
Results are usually done in radians instead of degrees. Have you tried doing your