Stage 2 · New Numbers / #11
Parallelogram Area: One Cut, One Slide
Coming soon
The video is in production. Follow along on GitHub to hear when it is out.
The idea
Cut off a triangle along the height and slide it to the other side, and the parallelogram becomes a rectangle; its length is the base and its width is the height, with the slanted side hidden inside, so the area is base times height.
A common mix-up
A parallelogram's area is base times slanted side, just like a rectangle's length times width.
Where it stops working
Squash the parallelogram down: the base and slanted side stay the same, but the area shrinks to zero, while base times slanted side doesn't change at all.
School year
China 5