Question #N402
A circle with center O has a radius of 5. A chord AB of the circle has length 8. What is the distance from O to the chord AB?
A. 2
B. 3
C. 4
D. 5
Correct Answer is: B
Draw a segment from O perpendicular to chord AB, intersecting AB at point M. Since the perpendicular from the center of a circle to a chord bisects the chord, AM = MB = 4. Triangle OAM is a right triangle with OA as the hypotenuse and AM as a leg. By the Pythagorean Theorem, . Therefore, OM = 3.