Instructions.
Use the slider \(k\) at the top left to change the linear scale factor of the blue parallelogram. You can also click and drag the vertices of the original yellow parallelogram (\(P\text{,}\) \(Q\text{,}\) and \(R\)) to change its shape.
Observe the dynamically calculated bases (\(b\) and \(b'\)) and perpendicular heights (\(h\) and \(h'\)). Notice how the Area Scale Factor perfectly matches the square of the linear scale factor (\(k^2\)) no matter how you reshape the original figure.