A circle's center is at (7 ,2 )(7,2) and it passes through (5 ,8 )(5,8). What is the length of an arc covering (7pi ) /4 7π4 radians on the circle?

1 Answer
Aug 7, 2016

=34.76=34.76

Explanation:

So the distance between points (7,2)(7,2) and (5,8)(5,8) is the radius of the circle.
So the distance is
=sqrt((7-5)^2+(8-2)^2=(75)2+(82)2
=sqrt(2^2+6^2)=22+62
=sqrt(4+36)=4+36
=sqrt40=40
=6.32=6.32
Therefore radius of the Circle r=6.32r=6.32
The Circumference of the circle=2pir=2pi(6.32)=39.73=2πr=2π(6.32)=39.73
An Arc covers 7pi/47π4 radians
or
It covers 7pi/4-:2pi=7/87π4÷2π=78 of the Circumference
Therefore; Length of the Arc=7/8(39.73)=34.76=78(39.73)=34.76