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How to Find the Arc Length of a Graph

In geometry, an arc is the portion of a circle who end points intersect the rays created by the vertex of an angle. An arc length is the length of that segment of the circumference of the circle and is defined by the equation (s / r) = θ, where s is the arc length, r is the radius of the circle and θ is the degree of the angle.

Instructions

- 1
  Use the known angle and radius values from the graph to set up the arc length equation: (s / r) = θ, through substitution.
- 2
  Solve for s by multiplying both sides by r resulting in the equation: s = rθ. Multiply the angle measure by the radius to find the arc length.
- 3
  Convert the answer to radians, if necessary, by multiplying the degree of the angle by (PI / 180°). For example, 25° = 25° * (PI / 180°) = 0.436 radians.
- 4
  Convert the answer to degrees, if necessary, by multiplying the radian measure of the angle by (180° / PI). For example, 3 rad = 3 rad * (180° / PI) = 171.9°.

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