Cycloidal Curves: Theory, Parametric Equations, and Animation

The purpose of this post is to systematically derive the corresponding parametric equations and implement them in Python for visualization using Manim and Matplotlib. The goal is not only to understand these curves analytically but also to see them come alive through animation.

cardioid_fixed_visible_800px.gif
Cardioid ($r = R$), a special case of the epicycloid.

 

The Intuition Behind Integration by Parts (Proof & Example)

Many students simply memorize the Integration by Parts formula: ∫ u dv = uv - ∫ v du, but understanding where it comes from makes it much easier to remember and apply during exams.

1. The Intuitive Proof (Reverse Product Rule)

The entire concept is actually just the Product Rule for differentiation in reverse.
From the product rule for two differentiable functions, u and v: (uv)' = u'v + uv'