How do I find the angle from an involute in Excel?

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Discussion Overview

The discussion revolves around finding the angle from an involute using Excel, specifically focusing on the mathematical formulation and numerical solutions related to transcendental equations. Participants explore the implications of different interpretations of the formula and seek practical solutions for calculations without relying on external tables.

Discussion Character

  • Exploratory, Technical explanation, Homework-related, Mathematical reasoning

Main Points Raised

  • One participant presents a formula for the involute of an angle, questioning how to solve for the angle given the involute.
  • Another participant seeks clarification on the correct interpretation of the formula, emphasizing the importance of parentheses in mathematical expressions.
  • A third participant confirms the interpretation of the formula as tan(theta) - pi*theta/180.
  • One participant notes the complexity of obtaining a formula solution for a transcendental equation, suggesting that a numerical solution may be more feasible.
  • A later reply indicates a need for a numerical answer, describing a specific scenario involving an Excel spreadsheet and the desire to avoid looking up values in a table.

Areas of Agreement / Disagreement

Participants express differing views on the correct formulation of the involute equation and the feasibility of obtaining a formula solution, indicating that multiple competing interpretations and approaches remain unresolved.

Contextual Notes

The discussion highlights the challenges associated with transcendental equations and the limitations of obtaining analytical solutions, as well as the specific context of using Excel for calculations.

Who May Find This Useful

Individuals interested in mathematical modeling, numerical methods, or those working with Excel for engineering or design applications may find this discussion relevant.

NotToSmart
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This is my first post and I am not sure how to get the math symbols used in formulas.
The formula for the involute of an angle is: involute of theta = tangent of theta - pi * theta / 180.
If I know the involute of theta how do I solve for theta?
 
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Is that tan(theta- pi*theta/180) or tan(theta)- pi*theta/180?? Parentheses are important!

Guessing that it is the former, use the arctan!
 
No it is the latter tan(theta)- pi*theta/180

example .014904=tan(20)-pi*20/180
 
Hmm, now that's much harder. In general you cannot get a "formula" solution to a transcendental equation, which this is, with the unknown both inside and outside a transcendental function (tangent). A numerical solution is probably the best you can do.
 
A numerical answer is what I am looking for in the end. This is the situation. I have an Excel spreadsheet with some formulas for figuring the measurement over wires of special thread forms. One formula gives me the involute of an angle. I then have to look up the coresponding angle in a table and enter that angle in the next formula. I am trying to come up with a way to calculate the angle without having to look in the table. If the angle is accurate to three decimal places this should be fine for my needs. I would greatly appreciate any help
 

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