Solving Quadrilaterals with Known Angles & 1 Side

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Discussion Overview

The discussion revolves around the problem of determining the lengths of the sides of a quadrilateral when all four angles and one side are known. Participants explore the implications of this information on the shape and dimensions of the quadrilateral, considering various configurations and examples.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions how to solve for the remaining sides of a quadrilateral given all angles and one side, expressing difficulty in finding a solution.
  • Another participant suggests that the shape should be determined by the known data, implying that knowing which two angles the given side is between could help, but they do not recall a specific formula for the lengths of the other sides.
  • A different participant argues that it is not possible to uniquely determine the quadrilateral, using the example of a quadrilateral with all right angles to illustrate that the figure could be either a square or a rectangle, depending on the lengths of the other sides.
  • Further elaboration is provided by another participant, who describes a scenario where the fixed side is set to length one and discusses extending sides to infinity, indicating that this leads to an uncountable number of possible configurations for the quadrilateral.
  • One participant acknowledges the mental picture presented by another, while also noting the simplicity of the rectangle as a specific case.

Areas of Agreement / Disagreement

Participants generally disagree on the ability to determine the lengths of the other sides of the quadrilateral based on the given information. Multiple competing views remain regarding the implications of the known angles and side.

Contextual Notes

The discussion highlights limitations in determining unique solutions based on the provided data, particularly the dependence on the specific configuration of angles and the chosen side.

Physics is Phun
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to solve a quadrilateral when you know all four angles and one side? I can't seem to find any way to solve the other 3 sides in this one question I am working on.
thanks :biggrin:
 
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seems that it should be determined by that data, i.e. the shape should be determiend and then you have one side to set the scale, provided you know which two angles the given side is between. but a formula has not come to mind yet for their lengths.


Wait! what about a rectangle!?
 
Last edited:
No, it's not possible. For example, suppose that all of the angles were right angles. You have one side's length, but how would you know whether the figure is a square or a rectangle? You can't. Suppose the side you are given has length 1, and all the angles are right. The side across from the given side must be 1, but the other two could be anything.
 
mathwonk said:
Wait! what about a rectangle!?

Or any other quadrilateral for that matter:

assume that the fixed side is length one and as drawn in the plane is the interval [0,1] on the x axis. extend the sides incident to the ends of this segment to infinity, and draw any line parallel to the side "opposite" our fixed side, then all angles are the same and the other sides can be an uncountable number of options.
 
yeah that mental picture conviced me but i thought i would just mention the easy one.
 

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