The radius is half of the diameter, so to convert the diameter to the radius, you would divide it by two. You need to know the radius if you want to find the area of a circle. The formula for finding the area of a circle is Pi times the radius squared. The diameter of the circle is the length from one side of the circle to the other side, so the radius is the length from the center of the circle to an outside edge. The circumference of the circle is the length around the entire circle.
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Q&A Related to "Convert Diameter to Radius?"
 take half of it take half of it http://wiki.answers.com/Q/How_do_you_convert_a_dia...
 1. Take the circumference of a circle and divide it by Pi. For example, if the circumference is 12.56, you would divide 12.56 by 3.14159 to get 4, which is the diameter of the circle http://www.ehow.com/how_5892744_diameter-radius-ci...