Question:
I am working on a project concerning parabolic mirrors. I need to create a mirror to focus sunlight on a focal point, but I don't know how to do it. Is there some equation that tells where a focal point will be in relation to a parabola?

What is a directrix?

Hi Andy,

In the Resource Room at Math Central is a resource called Why are satellite dishes parabolic?. I think it will answer your questions.

Cheers,
Penny