Determine angle of intersecting lines inside a circle

In summary, the author ran into a problem where they could not determine the value of x. They added some other variables and found four equations that when combined produced 360. Two of these equations related to length and one related to degrees. However, due to the lack of information, they were unable to solve for x.
  • #1
2milehi
146
20
So I ran across this problem on the 'net and I can't determine "x". The arc length of the circle is 360.

untitled.png


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
 
Physics news on Phys.org
  • #2
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.)
 
  • #3
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.
 
  • #4
Can anyone else figure it out?
 
  • #5
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.
 

FAQ: Determine angle of intersecting lines inside a circle

How do you find the angle of intersecting lines inside a circle?

To find the angle of intersecting lines inside a circle, you can use the formula angle = (arc length / radius) * (180° / π). This formula works for both central angles and inscribed angles.

What is the difference between a central angle and an inscribed angle?

A central angle is formed by two radii of a circle, while an inscribed angle is formed by two chords of a circle. Central angles are measured from the center of the circle, while inscribed angles are measured from the circumference of the circle.

Can you determine the angle of intersecting lines inside a circle without knowing the radius?

Yes, you can use the formula angle = (arc length / chord length) * (180° / π) to find the angle of intersecting lines inside a circle without knowing the radius. This formula is useful when the radius is not given or cannot be easily measured.

How do you find the measure of an inscribed angle if you know the measure of the central angle?

The measure of an inscribed angle is always half of the measure of its corresponding central angle. For example, if the central angle measures 60°, the inscribed angle will measure 30°. This relationship holds true for all inscribed angles in a circle.

Can you have two different inscribed angles with the same measure?

Yes, it is possible to have two different inscribed angles with the same measure. This occurs when the two angles are formed by different chords that intercept the same arc of the circle. In this case, the inscribed angles will be congruent (have the same measure).

Similar threads

Replies
7
Views
4K
Replies
2
Views
1K
Replies
4
Views
1K
Replies
29
Views
2K
Replies
9
Views
1K
Replies
14
Views
2K
Replies
1
Views
2K
Back
Top