5.1.2

Arc length

Test yourself

Arc Length of a Sector

We can find the arc length of a sector of a circle given the radius of the circle and the angle of the sector.

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Arc length

  • The length of the arc of a sector of a circle is equal to the radius rr multiplied by the angle θ:
    • s=rθs = r\theta
  • Where the angle θ is measured in radians.
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Example

  • What is the arc length, ss, of the sector with angle θ=2π5\theta = \frac{2\pi}{5} radians and radius 4.5 cm?
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Arc length

  • The equation for arc length is s=rθs = r\theta.
  • Substituting in, we get:
    • s=4.5×2π5=9π5=5.65s = 4.5 \times \frac{2\pi}{5} = \frac{9\pi}{5} = 5.65 cm (2 d.p.)

Jump to other topics

1Proof

2Algebra & Functions

2.1Powers & Roots

2.2Quadratic Equations

2.3Inequalities

2.4Polynomials

2.5Graphs

2.6Functions

2.7Transformation of Graphs

2.8Partial Fractions (A2 Only)

3Coordinate Geometry

4Sequences & Series

5Trigonometry

6Exponentials & Logarithms

7Differentiation

8Integration

9Numerical Methods

10Vectors

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