Question

How many points determine a plane?

Answer 1

A plane is basically just a sheet of paper. Now imagine there's just a point floating in air. Now you can move the paper in any way you want and have that point be in the paper.

Now imagine two points floating in air, not moving. You can put the paper on those points and then rotate the paper around the points like this:



now add a third point and now you can't rotate the plane anymore, only slide it within the plane.