Question #N383
A circle with center O has a radius of 5. A chord AB of the circle is 8 units long. What is the distance from the center O to chord AB?
A. 2
B. 3
C. 4
D. 5
Correct Answer is: B
Draw a radius from O to point A and a radius from O to point B. Draw a segment from O perpendicular to AB, and let the point of intersection of the segment and AB be point C. Triangle AOC is a right triangle with hypotenuse OA = 5 and AC = 4. By the Pythagorean Theorem, OC = \sqrt{5^2-4^2} = \sqrt{9} = 3.