# Math Help - rewrite equations

1. ## rewrite equations

Ok, I have decided to go back to upgrade my marks from H.S. and wow has the math changed since the early 80's.

anyways how do I figure out the radius of a ball given only the circumference which is 13.2 mm

2. Originally Posted by mwalker11
Ok, I have decided to go back to upgrade my marks from H.S. and wow has the math changed since the early 80's.

anyways how do I figure out the radius of a ball given only the circumference which is 13.2 mm
you should know the formula: $\mbox { Circumference } = 2 \pi r$ .......where $r$ is the radius

plug in the circumference and solve for $r$