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3 years ago

A

Mathematics

1 answer:

Gnesinka [82]3 years ago

7 0

Answer:

A: 779 cm²

B: 1837 cm²

Step-by-step explanation:

For both problems, use the formula for surface area of a cylinder:

SA = 2πr² + 2πrh

2πr² is the two bases.

2πrh is the curved surface.

PROBLEM A

"the cylinder is 60 cm long" is h = 60.

If given diameter, you can find "r" by dividing it by 2. d = 2r

Given d = 4, then r = 2.

SA = 2πr² + 2πrh

SA = 2π2² + 2π2(60)

SA = 8π + 240π Add

SA = 248π Exact answer

SA ≈ 779.114978 Answer on calculator

SA ≈ 779 Rounded answer

Remember to include the units.

The surface area is about 779 cm².

PROBLEM B

"80 cm long" h = 80.

"circumference of 22 cm". C = 22. Remember C = 2πr. Find "r".

C = 2πr

22 = 2πr

11 = πr

r ≈ 11/π

SA = 2πr² + 2πrh

SA = 2π(11/π)² + 22(80) Substitute 2πr with the circumference.

SA ≈ 1837.030992 Answer on calculator

SA ≈ 1837 Rounded answer

Remember to include the units.

The surface area is about 1837 cm².

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