1. The problem statement, all variables and given/known data A bead slides without friction on a circle in the shape of cycloid with equations x=a(B-sinB) and y=a(1+cosB) where 0<=B<=2pi. Find the lagrangian. 2. Relevant equations 3. The attempt at a solution I've tried to solve that problem by converting the positions x and y from cartesian coordinate to a new system of coordiantes defined by those equations. The problem is that am having many long calcucaltions. My new idea is to work it out in the polar coordinates. Am i going in the roght way?