Find the surface area of a rectangular parallelepiped if its length is 9 cm, width is 4.5 cm and height is 8.1 cm.

First of all, it is imperative to write down the formula to determine the total surface area of a rectangular parallelepiped. T. to. the faces of this figure are rectangles (sometimes squares), and every two opposite faces are equal to each other, then the formula takes the form:

S p.p. = 2 * (a * b + a * c + b * c).

If a = 9 cm, b = 4.5 cm, c = 8.1 cm, then:

S p.p. = 2 * (9 * 4.5 + 9 * 8.1 + 4.5 * 8.1) = 2 * (40.5 + 72.9 + 36.45) = 2 * 149.85 = 299.7 (cm 2).

Answer: S p.p. = 299.7 (cm 2).