Find the exact length of the curve (polar)...

r = 2cosθ ; 0 ≤ θ ≤ π

I got 4π ... was I close?

The arc length equals
∫ √(r^2 + (dr/dθ)^2) dθ
= ∫(θ = 0 to π) √((2 cos θ)^2 + (-2 sin θ)^2) dθ
= ∫(θ = 0 to π) √(4 (cos^2(θ) + sin^2(θ))) dθ
= ∫(θ = 0 to π) 2 dθ
= 2π.

I hope this helps!