Determine if point lies on inscribed square

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Discussion Overview

The discussion revolves around determining whether a point lies on the sides of a square that is inscribed in a circle, given only the radius of the circle centered at the origin. Participants explore different approaches to the problem, including geometric intuition and mathematical reasoning.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests finding the equations for each side of the square and testing the given point, but acknowledges the ambiguity in how a square can be inscribed in various orientations.
  • Another participant proposes an intuitive approach, indicating that points inside a smaller circle do not belong to an inscribed square, while points between two circles do belong to an inscribed square, though this requires clarification on the radius of the circles involved.
  • A participant expresses confusion about the concept of a smaller circle appearing when the square is shifted, questioning the relationship between the square's endpoints and the circle.
  • Clarification is provided that the square is rotated rather than shifted, and that the sides of the square create an inscribed circle, which could aid in finding an equation for this circle.
  • One participant indicates they have gained understanding after considering an animation related to the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best approach to determine if a point lies on the sides of the inscribed square, and there are competing views regarding the geometric relationships involved.

Contextual Notes

There are unresolved assumptions regarding the definitions of the circles and squares involved, as well as the specific conditions under which a point is considered to lie on the sides of the square.

ged25
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How do you determine if a point lies on the sides of a square inscribed on a circle ?
I'm given only the radius of the circle and the circle is centered at the origin.
My idea was to find the equation for each side and then to test the given point.
However, I just realized that you can inscribe a square in many different ways.
I'm stumped on how to do this.
 
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Do you mean "determine if a point lies on A certain square" or on a specific square? If you need to prove the last, then you really need some more information.

The first question is a bit more fun. Try to see it intuitively first. Draw an inscribed square and mentally change the square to another inscribed square. You will see that you get a second (smaller) circle. Points lying inside the circle do not belong to a inscribed square, and points lying inbetween the cricles do belong to a insribed square.
The only thing you need to do now is to find the radius of the circle.

I'm sorry if you understood nothing of what I tried to describe, but it's hard to explain. I suggest download the free program geogebra and play a bit with it. You'll see very soon what I mean...
 
Its the first question.
I do not understand how you can get a smaller circle when you shift the square. Maybe I'm doing it wrong but I thought that when you shift the square, the end points of the square move along the circle. The diagonals of the square will be equal to the diameter of the circle and will remain the same regardless of the square is drawn.
 
You don't shift the square, but you rotate the square. But perhaps you meant that.
It's true that the endpoints of the square will still lie on the circle, but the sides of the square will create an inscribed circle. The side of every inscribed square will be a tangent line to this inscribed circle. This fact would make it easy to find an equation for this circle...
 
Ok, I get it now. I seem to vaguely remember an animation that showed this.
 

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