Double the Radius - Quadruple the Area
- Linda Fahlberg-Stojanovska
Doubling the radius or the diameter of a circle quadruples the area! Change the radius of the big circle using the slider. The smaller circle always has "half" that radius. But the area of the big circle is 4 times the area of the small circle.
You know that doubling the side of a square quadruples the area. This shows that the same thing is true with the radius or the diameter of a circle. Can you figure out why this is true? Think about the formula for the area of a circle.