Question

in 17-19, apply the formula for surface area of a cylinder $sa = 2b + ph$.

1. find the amount of wrapping paper you need to wrap a gift in the cylindrical box shown. you need to cover the top, the bottom, and all the way around the box. use 3.14 for $pi$, and round to the nearest tenth.

(the cylinder has a height of 8 in. and a radius of 9 in.)

Explanation:

Step1: Calculate base area $B$

The base is a circle with radius $r=9$ in.
$B = \pi r^2 = 3.14 \times 9^2 = 3.14 \times 81 = 254.34$ in²

Step2: Calculate perimeter $P$ (circumference)

$P = 2\pi r = 2 \times 3.14 \times 9 = 56.52$ in

Step3: Calculate lateral surface area $Ph$

Height $h=8$ in.
$Ph = 56.52 \times 8 = 452.16$ in²

Step4: Calculate total surface area $SA$

$SA = 2B + Ph = 2 \times 254.34 + 452.16 = 508.68 + 452.16 = 960.84$ in²

Step5: Round to nearest tenth

Round 960.84 to one decimal place.

Answer:

960.8 square inches