Math surface area problem?

Question

Using pi=3.14 find the surface area of the cylindrical cake, excluding its base.

The hight is 12 inches and the diameter is 30 inches and the radius is 15 inches

Answer 1

The cylinder cake height     : h = 12 inches

The cylinder cake diameter : d = 30 inches

The cylinder cake radius     : r = 15 inches

The surface area of the cylinder cake : A = 2π×r² + 2π×r×h

A = 2π×r(r + h)

Substitute π = 3.14 , h = 12 , r = 15 in the above formula

There fore A = 2(3.14)(15)(15 + 12)

Simplify

               A = 30(3.14)(27)

               A = 2543.4sq.inches

Comments

A = 1836.9 squre inches.

Answer 2

The cylindrical cake height = 12 inches

cylindrical cake diameter : d = 30 inches

cylindrical cake radius = 15 inches.

In this case surface area of the cylinder cake : A = (area of top) + (perimeter of top )* height

A = π r² + 2 π r h

A = 3.14 (15)² + 2(3.14)(15)(12)

A = 706.5 + 1130.4

A = 1836.9 squre inches.