Is the lateral area of a cylinder a triangle?

Step-by-step explanation:

no, it is a rectangle or square but mostly rectangle.

Step-by-step explanation:

For a right circular cylinder of radius r and height h, the lateral area is the area of the side surface of the cylinder: A = 2πrh. For a pyramid, the lateral surface area is the sum of the areas of all of the triangular faces but excluding the area of the base.