# Math Help - Circle and three lines

1. ## Circle and three lines

Hello everyone I am new to the forums. I didnt know where to put this one, either in the high school or college section.

I was wondering if you guys/gals can help me out with this problem.
I dont really know how to start the problem.

here you go:

We are given three infinite straight lines. we need to construct a circle that touches the first two lines and has its center on the third line?

Any help is appreciated.

thanks everyone

joe

2. Originally Posted by joesmith13610
Hello everyone I am new to the forums. I didnt know where to put this one, either in the high school or college section.

I was wondering if you guys/gals can help me out with this problem.
I dont really know how to start the problem.

here you go:

We are given three infinite straight lines. we need to construct a circle that touches the first two lines and has its center on the third line?

Any help is appreciated.

thanks everyone

joe
what do we know about the lines? are they parallel, perpendicular, skew? was that all the info you were given?

3. Hello, Joe!

Welcome aboard!

We are given three infinite straight lines.
We need to construct a circle that is tangent to the first two lines
and has its center on the third line.
Code:
               L2 /                   /
/                   /
/                   ♥ C
/                 o /
/               o   /
/             o     /
/           o       /
/         o         / L3
/       o           /
/     o             /
/   o               /
L1     / o                 /
- - * - - - - - - - - - * - - - - - -
/                   /
/                   /
Assuming that the lines intersect . . .

Construct the bisector of the angle formed by $L_1$ and $L_2.$
. . The center of our circle lies on this angle bisector.

Locate the intersection $C$ of the angle bisector and $L_3.$
. . $C$ is the center of the circle

Determine the perpendicular distance from $C$ to $L_1$ (or to $L_2$).
. . That is the radius of the circle.

4. Originally Posted by Jhevon
what do we know about the lines? are they parallel, perpendicular, skew? was that all the info you were given?

that was all the info we got.

joe