Geometry
GradesGrade 7GeometryArea & Circumference of Circles

Area & Circumference of Circles

📐 Geometry
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Area & Circumference of Circles

Every circle is governed by π — use it to find circumference and area.

The circumference of a circle is the distance around it, and the area is the space enclosed. Both formulas involve π (pi), the ratio of circumference to diameter, approximately 3.14159.

C=2πrA=πr2C = 2\pi r \qquad A = \pi r^2
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Radius r = half the diameter. Diameter d = 2r.

🍕Pizza circle calculations
A pizza has a diameter of 14 inches, so r = 7 inches.

Circumference = 2π(7) = 14π ≈ 43.98 in
Area = π(7²) = 49π ≈ 153.94 in²
C=2π(7)=14π≈43.98 inC = 2\pi(7) = 14\pi \approx 43.98 \text{ in}
A=π(7)2=49π≈153.94 in2A = \pi(7)^2 = 49\pi \approx 153.94 \text{ in}^2

Circumference

Formula: C = 2πr or C = πdUnit: linear (cm, in, m)Measures the distance around the circle

Area

Formula: A = πr²Unit: squared (cm², in², m²)Measures the space inside the circle

Circumference is a length; area is a surface measurement — always check which one the problem asks for.

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Remember This!

Leave answers in terms of π (like 49π) for exact answers, or multiply by 3.14 for decimal approximations. Problems will specify which form they want.

✏️ Try It!

A circular garden has a radius of 5 m. What is its area? (Leave in terms of π.)

Practice with CalcVerse
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