2D shapes can be found printed in a book or on a website. 2D shapes have sides and corners. A rectangle has 4 straight sides and 4 corners. A square is a special type of rectangle, where all 4 ...

Rectangles, arches, and triangles are the most common shapes used to build big structures. What happens when you push the side of a rectangle? The rectangle is a wobbly, unstable shape.

But to mathematicians, shapes encompass a vast universe of surprising forms, from one-dimensional loops to polytopes (geometric objects with flat sides that can exist in any desired dimension).