A circle has a chord that goes from ( pi)/2 to (13 pi) / 6 radians on the circle. If the area of the circle is 5 pi , what is the length of the chord?

1 Answer
Jun 27, 2018

The length of the chord is sqrt5.

Explanation:

Let the center of the circle be point O. Let the point at pi/2 be point A and let the point at (13pi)/6 be point B. Since (13pi)/6=2pi+pi/6, point B can be thought of as located at an angle of pi/6. Therefore, m/_AOB=pi/2-pi/6=pi/3. Since points A and B are located on the circle, OA=OB because they are both radii. Since OA=OB, we know that m/_OAB=m/_OBA and since m/_AOB=pi/3, we know that m/_OAB=m/_OBA=m/_AOB=pi/3 and that OA=OB=AB.

The area of a circle is given by A=pir^2 so we know 5pi=pir^2 or that r=sqrt5. Since OA=r=sqrt5 and chord AB=OA, AB=sqrt5.