A circle has a chord that goes from pi/3 π3 to pi/2 π2 radians on the circle. If the area of the circle is 9 pi 9π, what is the length of the chord?

1 Answer
Nov 7, 2016

Chord length is 1.55281.5528

Explanation:

As area of a circle is given by pir^2πr2 and it is 9pi9π, we have r=sqrt9=3r=9=3.

Now see the given figure. The angle subtended by the chord at the center is pi/2-pi/3=pi/6π2π3=π6.
enter image source here
If the chord length is aa and angle subtended by the chord at the center is thetaθ, the relation we have is

sin(theta/2)=(a/2)/rsin(θ2)=a2r or a=2rsin(theta/2)a=2rsin(θ2)

Hence, chord length is 2xx3xxsin(pi/12)=6xx0.2588=1.55282×3×sin(π12)=6×0.2588=1.5528