Cycloid - Equations

Equations

The cycloid through the origin, generated by a circle of radius r, consists of the points (x, y), with

\begin{align} x &= r(t - \sin t) \\ y &= r(1 - \cos t)
\end{align}

where t is a real parameter, corresponding to the angle through which the rolling circle has rotated, measured in radians. For given t, the circle's centre lies at x = rt, y = r.

Solving for t and replacing, the Cartesian equation would be

The first arch of the cycloid consists of points such that

When y is viewed as a function of x, the cycloid is differentiable everywhere except at the cusps where it hits the x-axis, with the derivative tending toward or as one approaches a cusp. The map from t to (x, y) is a differentiable curve or parametric curve of class C∞ and the singularity where the derivative is 0 is an ordinary cusp.

The cycloid satisfies the differential equation:

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