A circle's center is at (3 ,1 )(3,1) and it passes through (6 ,6 )(6,6). What is the length of an arc covering (13pi ) /12 13π12 radians on the circle?

1 Answer
Feb 17, 2016

19.84519.845

Explanation:

The radius of the circle is
color(white)("XXX")r=sqrt((6-3)^2+(6-1)^2) = sqrt(3^2+5^2) = sqrt(34)XXXr=(63)2+(61)2=32+52=34

Since a circle has a circumference (arc length) of 2rpi2rπ
and an arc angle of 2pi2π:
("arc length")/("arc angle") = (2rpi)/(2pi) = ("required arc length")/((13pi)/12)arc lengtharc angle=2rπ2π=required arc length13π12

"required arc length"=(13pi)/12*(cancel(2)rcancel(pi))/(cancel(2)(cancelpi))=(13pir)/12

color(white)("XXXXXXXXXXX")=(13sqrt(34)pi)/12

color(white)("XXXXXXXXXXX")~~19.845 (using a calculator)