Hello! Nice to meet you. I'm studying a Bachelor of Science and I have a doubt: A bead slides without friction on a frictionless wire in the shape of a cycloid with equations x = a(θ-sin θ) y = a(1+cos θ) where θ's range is 0 to 2π and a>0 a) Find the equation of motion: And I resolved: I checked in a physics book that the solution is correct b) Make the change of variable u= cos (θ/2) and find a linear equation for u(t). Solve this equation and find the solution θ(t) which in the case of a bead at t = 0 falls from rest from the corresponding point θ= π/2 I don't know how to make the change. Can anybody help me? Thanks and nice to meet you.