A circle's center is at (2,6) and it passes through (3,1). What is the length of an arc covering π3 radians on the circle?

1 Answer
Feb 21, 2016

arc length = radius x arc angle
radius = 26
arc angle = π3

arc length = 26(π3)5.34

Explanation:

First find the radius, r, using the equation of a circle:
(xx0)2+(yy0)2=r2

The circle's centre is (2,6), so x0=2andy0=6
The circle passes through (3,1), so at this point x=3 and y=1.

Inputting all this into the circle equation:
(32)2+(16)2=r2
(1)2+(5)2=r2
1+25=r2=26
Therefore: r = 26

Now we can find the arc length using:
arc length = radius x arc angle

arc angle = π3

arc length = 26(π3)5.34