The two triangles have the same area, half of the parallelogram. Image caption, The parallelogram can be cut to make a rectangle. The rectangle is made up of the two original triangles.

For example, a triangle made of paper would collapse much sooner ... What happens when you push the side of a rectangle? The rectangle is a wobbly, unstable shape. When you push the side, it ...

The surface area is made up of the end faces and rectangular ... One edge of the rectangle is the perimeter of the triangle. 3 + 4 + 5 = 12. The area of the combined rectangular faces is 7 × ...