If the length of the longest chord of a certain circle is 20, what is the radius of that certain circle? Choose the correct choice:
A) 2.5	B) 5	C) 10	D) 15	E) 20
Longest chord of a circle is the diameter of the circle   diameter = 2 * radius   If diameter of the circle is given as 20 = 2 * 10   so radius of the circle =10   correct answer - 10
<result>C</result>
If the length of the longest chord of a certain circle is 20, what is the radius of that certain circle?