Plotting a sphere using the online 3-D function grapher

[kfarouk]

Hi,
the equation of a sphere is x^2+y^2+z^2=r^2

so z^2=r^2-x^2-y^2

so z=sqrt(r^2-x^2-y^2)

I used this equation to plot a sphere or even a hemisphere but it gives me something similar to a sphere with curves at the edges.

please follow this url to view the function:

http://www.livephysics.com/ptools/onlin ... x-y%2Ay%29]Graph: sqrt(1-x*x-y*y)

Any help