The height of an equilateral triangular prism increases by one unit. The new lateral area is more than the original by how much?
Answer
the perimeter of the base
the area of the base
the height
the area of one lateral face
I will assume that by "lateral area" you mean the surface area without the two triangular bases
So if the side of the equilateral triangle is s and the height is h, then the area of the three rectangles is 3sh
new height is (h+1)
so new area = 3s(h+1)
= 3sh + 3s
so the increase is 3s, which is the "perimeter of the base"