A circle's center is at (3 ,5 )(3,5) and it passes through (2 ,8 )(2,8). What is the length of an arc covering (5pi ) /4 5π4 radians on the circle?

1 Answer
Nov 22, 2016

(5sqrt(10)pi)/4510π4

Explanation:

Part 1
If a circle has a center at (3,5)(3,5) and passes through (2,8)(2,8)
it has a radius of r=sqrt((3-2)^2+(5-8)^2)= sqrt(1+9)=sqrt(10)r=(32)2+(58)2=1+9=10

Part 2
An arc with an angle of kk radians
has a length of k/(2pi) xx "circumference of the circle"k2π×circumference of the circle
but since the "circumference of the circle" = 2pircircumference of the circle=2πr
the length of an arc with an angle of kk radians is k * r#

Part 3
For the given circle and arc
the arc length is (5pi)/4xxsqrt(10)5π4×10