Parametric, Polar & Vectors · Parametric Curves

Parametric Arc Length

L=αβ(dxdt)2+(dydt)2dtL = \int_\alpha^\beta \sqrt{\left(\frac{dx}{dt}\right)^2 + \left(\frac{dy}{dt}\right)^2}\, dt

The length of a parametric curve from t = α to t = β.

  • 2 variables
  • 2 worked examples
  • 12 in Parametric, Polar & Vectors

Variables

Variables used in the Parametric Arc Length formula
SymbolNameUnit
alphaStart parameter -
betaEnd parameter -

Worked examples

Find the circumference of x = cos t, y = sin t, 0 ≤ t ≤ 2π.
  1. dx/dt = -sin t, dy/dt = cos t
  2. √(sin²t + cos²t) = 1
  3. L = ∫₀^(2π) 1 dt = 2π

Answer:

1 more worked examplePremium

Find the length of x = t², y = (2/3)t³ for 0 ≤ t ≤ 2.

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Common questions

What is the Parametric Arc Length?

The length of a parametric curve from t = α to t = β. It is one of the parametric, polar & vectors formulas in the CalcRef reference.

What do the symbols in the Parametric Arc Length mean?

In the Parametric Arc Length, alpha is the start parameter; beta is the end parameter.

How do you use the Parametric Arc Length?

Worked example. Find the circumference of x = cos t, y = sin t, 0 ≤ t ≤ 2π. dx/dt = -sin t, dy/dt = cos t. √(sin²t + cos²t) = 1. L = ∫₀^(2π) 1 dt = 2π. Answer: 2π.

Practice

Quiz yourself on Parametric, Polar & Vectors

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