# Radius of a sphere section

Let’s cut a sphere by a variable plane parallel to the base plane at a distance *h* from the center of the sphere. The section of the sphere by the plane is a circle of radius *r*.

Let’s represent the variations of *r* in function of *h*, in the system of axes (represented in the horizontal plane).

What is the graph of the function *r(h)* ? Justify the answer.

Hint : move the point *H* and observe the trajectory of the point of coordinates *(h, r)* in the axes.