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The volume of a cylinder closed at one end is 1056 cm³. If its height is 21 cm, find its: (I) diameter (ii) total surface area

a) Diameter: 8 cm, Total Surface Area: 1233 cm²
b) Diameter: 12 cm, Total Surface Area: 1452 cm²
c) Diameter: 14 cm, Total Surface Area: 1572 cm²
d) Diameter: 10 cm, Total Surface Area: 1334 cm²

1 Answer

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Final answer:

The diameter of the cylinder is approximately 8 cm and the total surface area is approximately 193.624 cm².

Step-by-step explanation:

To find the diameter and total surface area of a cylinder, we first need to calculate its volume. The formula for the volume of a cylinder is V = πr²h, where V is the volume, r is the radius, and h is the height. In this case, the volume of the cylinder is given as 1056 cm³ and the height is 21 cm. Plugging in these values, we can solve for the radius:

1056 = 3.142 × r² × 21

Divide both sides by 3.142 × 21:

r² = 2

Take the square root of both sides:

r = √2

The diameter of the cylinder is twice the radius, so the diameter is 2√2. To find the total surface area, we use the formula A = 2πrh + πr², where A is the total surface area. Plugging in the values, we get:

A = 2 × 3.142 × √2 × 21 + 3.142 × (√2)²

A = 2 × 3.142 × √2 × 21 + 3.142 × 2

A = 2 × 3.142 × √2 × 21 + 6.284

Finally, we can calculate the total surface area:

A = 132.4√2 + 6.284

Simplifying further, we get:

A ≈ 132.4 × 1.414 + 6.284

A ≈ 187.34 + 6.284

A ≈ 193.624

Therefore, the diameter of the cylinder is approximately 8 cm and the total surface area is approximately 193.624 cm².

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