A circle's center is at (2 ,4 )(2,4) and it passes through (7 ,6 )(7,6). What is the length of an arc covering (15pi ) /8 15π8 radians on the circle?

1 Answer
Nov 4, 2016

Length of the arc: 31.731.7 (approx.)

Explanation:

If the circle has a center at (2,4)(2,4) and passes through (7,6)(7,6) then it has a radius of
color(white)("XXX")r=sqrt((7-2)^2+(6-4)^2)=sqrt(25+4) =sqrt(29)XXXr=(72)2+(64)2=25+4=29
and a diameter of
color(white)("XXX")d=2r=2sqrt(29)XXXd=2r=229

The circumference of the circle would be
color(white)("XXX")"Circumference"_circ=pid = 2sqrt(29)piXXXCircumference=πd=229π

The complete circle's circumference is covered by an arc of 2pi=(16pi)/82π=16π8

An arc of (15pi)/815π8 will cover ((15pi)/8)/((16pi)/8)=15/1615π816π8=1516 of "Circumference"_circCircumference

The given arc will cover
color(white)("XXX")15/16xx2sqrt(29)piXXX1516×229π

color(white)("XXX")~~31.72123912XXX31.72123912 (with a calculator)