<font face=TW Cen MT>Suppose a chord of a circle is 9 inches long and its midpoint is 6 inches from the center of the circle. Find the length of the radius.
How in the world do you figure that out?</font face=TW Cen MT>
You have a right triangle (centercircle, centercord, radius) You know two of the distances, solve for radius using the Pyh theorum .