A circle's center is at (2,4) and it passes through (3,1). What is the length of an arc covering 13π12 radians on the circle?

1 Answer
Feb 18, 2016

arc length = radius x arc angle
radius = 10
arc angle = 13π12

arc length = 10(13π12)10.76

Explanation:

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

The circle's centre is (2,4), so x0=2andy0=4
The circle passes through (3,1), so at this point x=3 and y=1.

Inputting all this into the circle equation:
(32)2+(14)2=r2
(1)2+(3)2=r2
1+9=r2=10
Therefore: r = 10

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

arc angle = 13π12

arc length = 10(13π12)10.76