Define Circle Knowing Two Points and ARC LENGTH Only.

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SUMMARY

The discussion focuses on determining the equation of a circle given two points on its circumference and the arc length between them, specifically in the context of a bending beam scenario. Two distinct solutions are identified: one utilizing Newton's approximation method and the other employing Taylor expansion. The most straightforward approach is identified as Newton's Method, which effectively calculates the radius based on the chord and arc lengths. Relevant resources include links to detailed explanations of these methods.

PREREQUISITES
  • Understanding of circle geometry, specifically chord and arc length relationships.
  • Familiarity with Newton's approximation method for solving equations.
  • Basic knowledge of Taylor series expansions.
  • Proficiency in trigonometry to visualize and solve the problem.
NEXT STEPS
  • Research "Newton's Method for circle equations" to understand its application in this context.
  • Explore "Taylor series expansion in geometry" for alternative solutions to circle-related problems.
  • Study "Chord length and arc length relationships in circles" for foundational knowledge.
  • Examine "Trigonometric methods for circle segment calculations" to enhance problem-solving skills.
USEFUL FOR

Mathematicians, engineers, and physics students dealing with circular motion or bending beams, as well as anyone interested in geometric problem-solving techniques.

Ryank
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I am having trouble doing exactly what the title says. I have two points and the arc length between them (this is a bending beam type of a situation). Essentially I know where the ends of the beam are and how long the bent beam is and I need to get the equation of the circle. And yes I realize there would be two distinct solutions depending on positive of negative curvature. Any help would be amazing, thanks!
 
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Ryank said:
I am having trouble doing exactly what the title says. I have two points and the arc length between them (this is a bending beam type of a situation). Essentially I know where the ends of the beam are and how long the bent beam is and I need to get the equation of the circle. And yes I realize there would be two distinct solutions depending on positive of negative curvature. Any help would be amazing, thanks!

What is the context of the question? Could you post a sketch? Thanks.
 
There doesn't really need to be a context. You know the length of a chord on the circle and the length of the arc segment between them. I did some digging and did finally manage to find two solutions. One uses Newton's approximation method and the other uses and taylor expansion:

http://norman.rasmussen.co.za/24/radius-from-arc-and-chord-length/
http://www.mathforum.com/dr.math/faq/faq.circle.segment.html#1
 
Last edited by a moderator:
Looks like case 1 from Dr. Math that requires Newton's Method is the most straightforward.
 
Last edited:
Perhaps this sketch will help, it's basic trigonometry.

Since you have fixed two points on the circumference you not only know the arc length you also know the chord length.
 

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