Circle Area in a Parallelogram
The Circle Area Visualizer dynamically visualizes the area formula of a circle. The user drags the center and a point to form a circle, which is automatically sliced into the given number of sectors. By dragging the sliders at the bottom or using the animation buttons, the user can rearrange the sectors into a pseudo-parallelogram, from which the area formula of a circle is derived. Below is the algebra behind the area formula of a circle, based on the parallelogram attained with the method that Circle Area Visualizer illustrates.
Note: The screenshots below were taken with Version 1.1 of the program.