# Math Help - Quadric Surface Problem

Let L be the line y=10, x=9z. If we rotate L around the x-axis, we get a surface whose equation is $Ax^2+By^2+Cz^2 = 1$, where
A = , B = , C =

I'm was able to find B and C. Need help with A.

2. Originally Posted by viet
Let L be the line y=10, x=9z. If we rotate L around the x-axis, we get a surface whose equation is $Ax^2+By^2+Cz^2 = 1$, where
A = , B = , C =

I'm was able to find B and C. Need help with A.
The point (9,10,1) lies on L and therefore on the surface. That gives you a relation that will determine A.

3. so to solve A, i set y & z to 0, and solve for A right?