A circle has a radius of \(5\) cm. What is its approximate area? Use \(\pi\approx3.14\).
- \(15.7\) cm\(^2\)
- \(31.4\) cm\(^2\)
- \(78.5\) cm\(^2\)
- \(314\) cm\(^2\)
Testinar Grade 6 math
Area of Circles Introduction
Students will build Grade 6 mastery of area of circles introduction using models, equations, and test-style reasoning.
CH04-08
Geometry
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- Date
- Score
- ____ / 8
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A circle has a diameter of \(12\) inches. What is the radius?
- \(3\) inches
- \(6\) inches
- \(12\) inches
- \(24\) inches
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What is the approximate area of Circle A? Use \(\pi\approx 3.14\).
- \(12.56\) cm\(^2\)
- \(25.12\) cm\(^2\)
- \(100.48\) cm\(^2\)
- \(50.24\) cm\(^2\)
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A circular pizza has a diameter of \(14\) inches. Which expression correctly represents its area?
- \(\pi \times 14^2\)
- \(2 \times \pi \times 14\)
- \(\pi \times 7\)
- \(\pi \times 7^2\)
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A circle has a radius of \(8\) meters. What is the approximate area using \(\pi \approx \frac{22}{7}\)?
- \(176\) m\(^2\)
- \(201\) m\(^2\)
- \(352\) m\(^2\)
- \(1408\) m\(^2\)
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If the radius of a circle is \(9\) inches, what is the diameter?
- \(4.5\) inches
- \(9\) inches
- \(18\) inches
- \(81\) inches
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A circular garden has a radius of \(6\) feet. What is the approximate area using \(\pi \approx 3.14\)?
- \(18.84\) ft\(^2\)
- \(37.68\) ft\(^2\)
- \(113.04\) ft\(^2\)
- \(226.08\) ft\(^2\)
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A circular pool has a radius of \(3\) feet. What is the approximate area using \(\pi \approx 3.14\)?
- \(9.42\) ft\(^2\)
- \(18.84\) ft\(^2\)
- \(28.26\) ft\(^2\)
- \(56.52\) ft\(^2\)
Answer key and explanations
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C. \(78.5\) cm\(^2\)
Area of a circle \(=\pi r^2\approx3.14\times5^2=3.14\times25=78.5\) cm\(^2\).
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B. \(6\) inches
The radius is half the diameter. \(r = \frac{d}{2} = \frac{12}{2} = 6\) inches.
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D. \(50.24\) cm\(^2\)
Using \(A = \pi r^2 \approx 3.14 \times 4^2 = 3.14 \times 16 = 50.24\) cm\(^2\).
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D. \(\pi \times 7^2\)
The diameter is 14 inches, so the radius is \(r = 7\) inches. Area \(= \pi r^2 = \pi \times 7^2\).
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B. \(201\) m\(^2\)
Area \(= \pi r^2 \approx \frac{22}{7} \times 8^2 = \frac{22}{7} \times 64 = \frac{1408}{7} = 201\frac{1}{7} \approx 201\) m\(^2\).
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C. \(18\) inches
The diameter is twice the radius. \(d = 2r = 2 \times 9 = 18\) inches.
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C. \(113.04\) ft\(^2\)
Area \(= \pi r^2 \approx 3.14 \times 6^2 = 3.14 \times 36 = 113.04\) ft\(^2\).
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C. \(28.26\) ft\(^2\)
Area \(= \pi r^2 \approx 3.14 \times 3^2 = 3.14 \times 9 = 28.26\) ft\(^2\).
