A circle is sliced into thin concentric rings which are cut and laid out side by side, forming a triangular shape whose base equals the circle's circumference and whose height equals the radius. The animation shows this triangle's area, one half base times height, simplifying to pi r squared. Useful for students learning where the circle area formula comes from rather than just memorizing it.
Narrated · 16:9 · every frame verified for overlaps, spacing and edges before rendering
Show how the area of a circle emerges by unrolling it into a triangle: circle with radius r, then the unrolled triangle, then the formula A = pi r^2.