Question

What is the surface area of this cylinder ?

Answer 1

88.0 mm² (nearest tenth)

Explanation:

Surface area of a cylinder =
`2\pi r^2+2\pi rh`

where:

• r = radius
• h = height

Given:

• r = 2 mm
• h = 5 mm

Substitute given values into the formula:

`\begin{aligned}\sf \implies SA & =2\pi (2)^2+2\pi (2)(5)\\ & = 8 \pi+20 \pi\\ & = 28 \pi\\ & = 88.0\:\sf mm^2\:(nearest\:tenth)\end{aligned}`

Answer 2

87.92 mm²

Explanation:

Given:

• Radius of circular base: 2 millimeters
• Height of cylinder: 5 millimeters

It should be noted:

• Surface area of cylinder: 2πrh + 2πr² (R = Radius; H = Height)

When the measures are substituted, we get the following expression:

• ⇒ 2π(2)(5) + 2π(2)²

Multiply the constants and substitute π as 3.14.

• ⇒ 20π + 2π(4)
• ⇒ 20π + 8π
• ⇒ 20(3.14) + 8(3.14)

Finally, simplify the expression to determine the surface area.

• ⇒ 20(3.14) + 8(3.14)
• ⇒ 62.8 + 25.12
• ⇒ 87.92 mm²