Problem:
Geometry-Circles (InterMath)

What happens to the circumference of a circle if you double the diameter?

If you triple the diameter?

If you halve the diameter?

As the diameter increases or (decreases) in measure, how does the circumference change?

Why does this change occur?

Solution:

Circumference of a Circle= 2 (pi) r = d (pi)

If I choose the diameter equal to 5C= 5(pi) (equals about 15.71)
If I double that diameterC= (2 * 5) pi= 10(pi) (equals about 31.42)
If I triple that diameterC= (3 * 5) pi = 15(pi) (equals about 47.12)
If I halve that diameterC= (5/2) pi = 2.5 (pi) (equals about 7.85)

There is a positive correlation between the diameter of a circle and the circumference of that same circle.

As the diameter increases, the circumference of that circle also increases.

As the diameter decreases, the circumference of that circle also decreases.

This change occurs because the diameter is the length of the widest part of the circle (the maximum distance from one point on a circle to another. One cannot change the diameter without changing the circumference (measure of the outside of the circle) of a circle.