Question

find the surface area of the outside of the block. taking out the drilled holes.

Answer 1

The surface area of the outside of the block is determined by the difference of cube and cylinder.

The surface area of cylinder is,

$S_c=\text{ 2}\Pi rh+2\Pi(r^2)$

The radius is 2 ft and height is 6 ft.

$S_c=2\Pi(2\times6+2^2)$$S_c=\text{ 2}\times3.14\times(12+4)$$S_c=100.48ft^{2^{}}$

The surface area of cube is,

$S_a=6s^2$

The sidde of cube is 6 ft.

$S_a=\text{ 6}\times6^2$$S_a=216ft^2$

The surface area of the outside of the block is,

$S=S_a-S_c$$S=\text{ 216-100.48}$$S=115.52ft^2$