Points (2 ,6 )(2,6) and (5 ,9 )(5,9) are (3 pi)/4 3π4 radians apart on a circle. What is the shortest arc length between the points?

1 Answer
Jan 10, 2018

Shortest arc length S = r * theta ~~color(red)(5.41)S=rθ5.41

Explanation:

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C = ((3pi)/4)C=(3π4)

Chord Ch = sqrt((5-2)^2 + (9-6)^2) = 4.2426Ch=(52)2+(96)2=4.2426

Using Pythagoras theorem,

r = Ch / (2* sin (C/2)) = 4.2426 / (2 * sin ((3pi)/8) = 2.2961r=Ch2sin(C2)=4.24262sin(3π8)=2.2961

Shortest arc length S = r * C = 2.2961 * ((3pi)/4) ~~color(red)(5.41)S=rC=2.2961(3π4)5.41