Question

geometry question.

Answer 1

@JoannaBlackwelder

Answer 2

Well, we have lots of isosceles triangles, but I'm not sure yet hoe to find the radius...

Answer 3

*how haha

Answer 4

Ok, yea, I saw that too. I used the secant tangent theorem and extended BD so it intercepts the circle at point F and FD=6 with that theorem.

And I hope that word was just a typo

Answer 5

Wouldn't you like to know? And I get FB=6. I think that is what you mean, right?

Answer 6

Oh yes, my typo

Answer 7

If we extend the line segment AB, we could make a secant line that crosses the other secant line.

Answer 8

this is what i found

Answer 9

and is this what you want to do?

Answer 10

Yup. :)

Answer 11

Because the products of the lengths of the secants are equal.

Answer 12

And since A is the center, A to the circle is a radius.

Answer 13

So, 4*6=r*(4+r-4)

Answer 14

Make sense?

Answer 15

i dont get the r*(4+r-4) part

Answer 16

Wait, that was wrong...just a sec.

Answer 17

Let's call the radius of the circle r.

Answer 18

So the piece of the secant that passes through A is r+4.

Answer 19

And the other piece of the secant is r-4.

Answer 20

So the equation is 6*4=(r+4)(r-4)

Answer 21

ok. but its not really a secant since it passes through the center. its a diameter

Answer 22

It is a diameter, but a diameter is just a special type of secant, right?

Answer 23

I 'm sorry, wrong terminology. I mean chord, not secant.

Answer 24

ok. i guess your right

Answer 25

You don't sound convinced. Do you not think my method is sound?

Answer 26

i know im convinced. i just didnt know a diameter was also a chord, but now im convinced

http://answers.yahoo.com/question/index?qid=20090221092517AAXylCx

Answer 27

ok. and when i solved it, i got 2 root 10

Answer 28

Yup, me too. :) Yeah, the diameter is the longest chord.

Answer 29

ok, so thats it?

Answer 30

Looks like it to me.

Answer 31

Is it supposed to be harder than that?

Answer 32

i dont think so. if only i knew a diameter was also a chord... but i did learned something new today. thank you so much!

Answer 33

Haha, no worries. :)