What is the arclength of the polar curve f(theta) = 2thetasin(5theta)-thetacot2theta f(θ)=2θsin(5θ)θcot2θ over theta in [pi/12,pi/2] θ[π12,π2]?

1 Answer
Jan 17, 2018

infty

Explanation:

For this solution, I am assuming that your ff is actually referring to the radial component.

If we travel an infinitely small angle, the distance will be f(thetaθ) dthetaθ. Therefore, we can integrate that function across that whole range to get the value, i.e. int_(pi/12)^(pi/2) f(theta)d theta π2π12f(θ)dθ

However, since cotangent goes to infinity very quickly at pi/2π2, this integral does not converge to a finite value, hence the length is infinite.