How do I solve diameter of a circle
Pie r square
Whatever your radius is, multiply by 2 (or double it). EX: radius= 2, diameter= 4.Formula to find the area of a circle: PI r squared.
It's the radius times 2. Example: If the radius of a circle is 4, then the diameter is 16.
Check here: http://www.mathgoodies.com/lessons/vol2/circumference.html