# Math Help - How do you kow that this triangle inside a circle is issocles ? is it a rule ?

1. ## How do you kow that this triangle inside a circle is issocles ? is it a rule ?

How can you say that the grey triangle is isosceles ?

2. ## Re: How do you kow that this triangle inside a circle is issocles ? is it a rule ?

Hello, MikeNoob!

How can you say that the grey triangle is isosceles?
Code:
              * * *
*           *
*               *
*                 *

*         O         *
*         ♥.        *
*         *:*.      *
*:::*.
*        *:::::*. *
*       *:::::::♥
*     *:::: *  B
* ♥ *
A

If $O$ is the center of the circle,
. . then $OA$ and $OB$ are equal radii.

3. ## Re: How do you kow that this triangle inside a circle is issocles ? is it a rule ?

Thanks for the reply Soroban So are you saying that "A triangle having two radii as its sides is always an isosceles ?"

4. ## Re: How do you kow that this triangle inside a circle is issocles ? is it a rule ?

Originally Posted by MikeNoob
Thanks for the reply Soroban So are you saying that "A triangle having two radii as its sides is always an isosceles ?"
come on Mike ... what do you say?

5. ## Re: How do you kow that this triangle inside a circle is issocles ? is it a rule ?

Haa.. after having a cup of coffee and reading your response, I realize this was an extremely dumb question. LOL... Thanks for that!!!

6. ## Re: How do you kow that this triangle inside a circle is issocles ? is it a rule ?

Originally Posted by MikeNoob
Thanks for the reply Soroban So are you saying that "A triangle having two radii as its sides is always an isosceles ?"
Think a bit...if OA = OB, then OAB is...?

7. ## Re: How do you kow that this triangle inside a circle is issocles ? is it a rule ?

@Richard.. I realize that I wasnt really thinking when posting this question..

8. ## Re: How do you kow that this triangle inside a circle is issocles ? is it a rule ?

Yeah, sorry, I think we posted right at the same time. We've all had those moments...