Calculating Arc Length for Polar Curve r = theta^(2)

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SUMMARY

The discussion focuses on calculating the arc length of the polar curve defined by r = θ² for the interval 0 ≤ θ ≤ π. The formula for arc length is provided as the antiderivative of the square root of the sum of the square of the function and the square of its derivative. The user successfully simplifies the expression to √(θ⁴ + 4θ²) and is advised to utilize a trigonometric substitution to facilitate the integration process. This approach is confirmed as a valid method to solve the problem.

PREREQUISITES
  • Understanding of polar coordinates and polar curves
  • Knowledge of arc length formulas in calculus
  • Familiarity with trigonometric identities
  • Experience with integration techniques, particularly trigonometric substitution
NEXT STEPS
  • Study trigonometric substitution methods for integrals
  • Review the derivation of arc length formulas in polar coordinates
  • Explore integral tables, specifically for irrational functions
  • Practice solving arc length problems for various polar curves
USEFUL FOR

Students studying calculus, particularly those focusing on polar coordinates and arc length calculations, as well as educators seeking to enhance their teaching materials on integration techniques.

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Homework Statement


Find the length of r = theta^(2) for 0<=theta<=pi


Homework Equations


Arc length s = antiderivative of sq rt (f (theta)^(2) + f (derivative theta)^(2))


The Attempt at a Solution


I have worked my way to the antiderivative of sq rt (theta^(4) + 4(theta)^(2)) but I'm not sure where to go from here. I've been looking for a trig identity that will help me thru the antiderivative and get rid of the sq. rt but haven't had any luck. Is there something I'm overlooking? Thanks in advance!
 
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You could rewrite it as

\sqrt{\theta^4 +4\theta^2} = \theta \sqrt{\theta^2 +4}

and use a trig substitution or look it up in a http://en.wikipedia.org/wiki/List_of_integrals_of_irrational_functions"
 
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Got it, thanks!
 

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