Verified answer

The lateral area is the area of just the circular outside of the cylinder, without

the ends. Imagine a piece of paper tightly wrapped around the outside of this

cylinder. If you unroll it, you have a rectangular piece of paper 20 inches long

(equal to the cylinder's height) and 10 inches wide (equal to the circumference

of the cylinder). The area of this piece of paper is 10 times 20, or 200 sq. in,

which is the same as the area of the lateral (curved) outside surface.

Hope this answers your question.