Geometry Question - Chords

[KateKnopp]

Geometry Question - Chords... I don't understand this at all. help please?

I was working on my homework, and I came across a problem I didn't understand (obviously). The question is:

A chord is 7 inches from the center of a circle with a radius of 12 inches. Find the length of the chord.

What I need to do is first draw it out to use as an example. It makes solving for me a lot easier. I understand how to draw it, I just don't know where the numbers have to go in order to solve the problem correctly. I could use help as soon as possible. Please and thank you!

 

[pka]

Go to this webpage.
Look at the formulas 6-9.

 

[KateKnopp]

I've tried that. My teacher didn't give us a formula or anything for it, she just explained it and expected us to know. I mean, I understood when she explained it, and now I'm just having a brain fart. I guess I just need a simple reminder on how to solve it.

 

[pka]

I've tried that. My teacher didn't give us a formula or anything for it, she just explained it and expected us to know. I mean, I understood when she explained it, and now I'm just having a brain fart. I guess I just need a simple reminder on how to solve it.

Did you look at formula #8?
You are given $\displaystyle R~\&~r$ are you not.
Think about it.

 

[pka]

I am sorry. I do not know how to do pictures or schematics or graphs on this site because I am a relatively new tutor.

Actually it is quit easy to use images on this site. Using any common graphics program such as PAINT to create a graphic.
Save it a as gif file to save space.

But there is no reason to reinvent the wheel.
There are many good images on the web.

 

[Deleted member 4993]

thanks pka I have paint and know how to use it

That sounds (well .... looks) like a threat!!!:evil:

 

[masters]

I was working on my homework, and I came across a problem I didn't understand (obviously). The question is:

A chord is 7 inches from the center of a circle with a radius of 12 inches. Find the length of the chord.

What I need to do is first draw it out to use as an example. It makes solving for me a lot easier. I understand how to draw it, I just don't know where the numbers have to go in order to solve the problem correctly. I could use help as soon as possible. Please and thank you!

Hi kateKnopp,

The distance from the center of your circle to the chord is the perpendicular distance. You could extend this to the edge of the circle to form a radius that is perpendicular to the chord.

Theorem: In a circle, a radius perpendicular to a chord bisects the chord.

Now, draw your two radii from the center to where the chord intersects the circle. You have formed two congruent right triangles. You know a leg (7 inches) and hypotenuse (12 inches). Use the Pythagorean theorem to find the missing leg. This value is half the length of the chord. Double this value and voila!