00:02
Okay, so we have an equation x squared plus what's going to explore.
00:06
So, okay, this is a circle in r2, but what does it represent in r3? we're first going to draw its graph in r2, x, y, z, the origin of o.
00:25
So the radius of the circle is 2.
00:32
So rapidly in r2, it goes like this.
00:35
So now, we didn't involve the coordinate z, but we can see that there's no z in the equation.
00:43
So the circle, x, x squared equals x squared plus y squared x4, is just a projection of the whole graph onto the x or y plane.
00:54
So now z is free...