Originally Posted by

**Anthonny** The problem says:

A swimming pool is circular with a 40-ft diameter. The depth is constant along east-west lines and increases linearly from 2ft at the south end to 7ft at the north end. Find the volume of water in the pool.

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I'm having trouble finding the equation of this plane. I would think two points are (0,20,7) and (0,-20,2).

However, I'm having trouble **finding a third point**. **<---- (20, 0, 4.5)**

I know that from three points I can find two vectors, then a normal vector, and then the equation of the plane.

Thank you.