If the length of the longest chord of a certain circle is 18, what is the radius of that certain circle?
Pick.
A) 2.5  B) 9  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 18 = 2 * 9   so radius of the circle = 9   correct answer - 9
<result>B</result>
If the length of the longest chord of a certain circle is 18, what is the radius of that certain circle?