Determine angle of intersecting lines inside a circle

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Discussion Overview

The discussion revolves around determining the angle "x" formed by intersecting lines inside a circle, given the arc length of the circle and several equations relating to the angles involved. The scope includes mathematical reasoning and problem-solving related to geometry and circle properties.

Discussion Character

  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents a set of equations involving angles and arc lengths, expressing difficulty in solving for "x" due to an indeterminate form.
  • Another participant suggests that the equations are not independent and indicates that the problem lacks sufficient information to determine a unique solution.
  • A third participant mentions that there is a provided answer that works for all angles and degrees of arc, implying that a solution exists despite the apparent complexity.
  • One participant reiterates the idea that the lack of information leads to an infinite number of solutions, emphasizing the dependence of variables.

Areas of Agreement / Disagreement

Participants generally agree that the equations presented are not independent and that there is insufficient information to arrive at a unique solution. However, there is a disagreement regarding the existence of a definitive answer, as one participant claims there is a solution that works for all cases.

Contextual Notes

The discussion highlights potential limitations in the problem setup, including the dependence of variables and the distinction between degrees of arc and lengths. The nature of the equations suggests that additional constraints or information may be necessary for a unique solution.

Who May Find This Useful

This discussion may be useful for individuals interested in geometry, particularly those exploring problems involving circles, angles, and the relationships between arc lengths and angle measures.

2milehi
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So I ran across this problem on the 'net and I can't determine "x". The arc length of the circle is 360.

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I added some other variable and took what I know about a circle and intersecting lines. I wound up with four variables and four equations.

x = 1/2 (y + 67)
w = 1/2 (z + 147)
y + z + 67 + 147 = 360
2w + 2x = 360

and into matrix form

1w + 1x + 0y + 0z = 180
0w + 1x - 1/2y + 0z = 67/2
1w + 0x - 0y - 1/2z = 147/2
0w + 0x + 1y + 1z = 146

But that comes up with an indeterminate.

Taking a closer look before I post, I see that three of the equations relate to length and one relates to degrees. But with s = r · theta, r is such that s = theta in degrees.

I am stuck now
 
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The reason you get "indeterminate" is that those four equations are not independent. And the problem itself does not have enough information. You could move that pretty much any where around the circle changing y and z but not x and w.

(Since you say "the arclength of the circle is 360" I suspect that y and z are in "degrees of arc", not length.)
 
There is an answer given for it and it does work out for all angles and degree of arc. So there should be a way to figure it out, hence why there is a measure of 147.
 
Can anyone else figure it out?
 
HallsofIvy said:
The reason you get "indeterminate" is that those four equations are not independent. And the problem itself does not have enough information. You could move that pretty much any where around the circle changing y and z but not x and w.

(Since you say "the arclength of the circle is 360" I suspect that y and z are in "degrees of arc", not length.)

It took a bit to sink in, but now I understand. There are an infinite number of solutions because of the lack of information.
 

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