how can a map a sphere on a 3D graph?
You mean to ask what is its equation?Originally Posted by Bad Apple
In xy co-ordinate system there is the x-co-ordinate and the y-co-ordinate. Thus, there are two dimensions. When mapping a sphere you need a third dimension. When studing Multivaraible Calculus you will be introduced to 3 dimensional graphs and vectors. The third variable introduced is z. The equation of a sphere is then,
$\displaystyle x^2+y^2+z^2=r^2$ where $\displaystyle r$ is its radius.