Intersecting lines are lines that meet at some point while perpendicular lines are intersecting lines that makes a right angle at the point of intersection.
Two line can either be intersecting or perpendicular. It is not possible to have two line that is neither intersecting or parallel.
In this question , it is given that we have a cylinder with with a radius of 9 and a surface area of approximately 791.68 units square.
The formula of surface area of cylinder is

Substituting the values of A and r, we will get

So the height of the cylinder is 5 units .
The number -5 is anything but natural number.
It is an integer (Z) ,a rational number (Q) and a real number (R) .
I hope this is right i think the answer is 40