A circle's center is at (7 ,2 ) and it passes through (5 ,6 ). What is the length of an arc covering (7pi ) /4 radians on the circle?

1 Answer
Sep 25, 2016

:. "Length of Arc="(7sqrt5pi)/2~~24.59"unit".

Explanation:

Let r be the radius of the circle.

The Centre C of the circle is C(7,2) and, the circle passes through

the pt.P(5,6). Hence, the dist. CP=r.

Using the Distance Formula, we get,

r^2=CP^2=(7-5)^2+(2-6)^2=4+16=20

:. r=sqrt20=2sqrt5.

Hence, the "Length of Arc CP=s="rtheta, where, theta is the

measure (in Radians ), of the /_ made by the "Arc "CP at the

Centre. We have, r=2sqrt5, &, theta=(7pi)/4.

:. "Length of Arc="2sqrt5*(7pi)/4=(7sqrt5pi)/2~~24.59"unit".