Question

This cylinder is cut by the plane shown. the plane is perpendicular to the base of the cylinder. what is the shape of the cross-section?

Answer 1

I cannot see your picture, but if the plane cutting the cylinder is indeed perpendicular to the cylinder's base, then the cross section must be square or rectangular. Going by the shape of most cylinders, I would guess that it is rectangular.

Answer 2

Rectangular

Explanation:

Given that a cylinder is cut by a plane.

The plane is perpendicular to the base.

Imagine a graph with a line y=r

This will be a horizontal line. When this is rotated between x=0 and x=h, we get a cylinder with radius =r and height =h.

When a plane cuts this cylinder the plane would be in xy plane a horizontal line.

So when a horizontal plane cuts the cylinder, we would get a planar closed shape which has opposite sides parallel and each angle 90 degrees.

Hence this will be a rectangle with length = h and width = r.

If h happens to be equal to r, in the special case, we may get a square.