1. The problem statement, all variables and given/known data Find the arc length of polar curve 9+9cosθ 2. Relevant equations L = integral of sqrt(r^2 + (dr/dθ)^2 dθ dr/dθ = -9sinθ r = 9+9cosθ )3. The attempt at a solution 1. Simplifying the integral r^2 = (9+9cosθ^2) = 81 +162cosθ + 81cos^2(θ) (dr/dθ)^2 = 81sin^2(θ) r^2 + (dr/dθ)^2 = 81 + 162cosθ + 81cos^2(θ) + 81sin^2(θ) 81sin^2(θ) + 81cos^2(θ) = 81 162 + 162cosθ = r^2 + (dr/dθ)^2 now I have to take the integral of the squareroot... Integral of sqrt(162 + 162cosθ)dθ chain rule..? (2/3)(162+162cosθ)^3/2*(162θ + 162sinθ) Integrated between 0 and 2pi...? which would lead to a crazy high number that I got as 3957501.966. Anyone know where I went wrong?