Topic Details (Notes format)

How to Calculate the Area of a Circle

Subject: Mathematics

Book: Maths Mastery

The area of a circle is given by the formula A = πr², where r is the radius—the distance from the center to the circumference. If you have a circle with radius 5 cm, its area is π × 5² = 25π cm². In practical terms, you might need to measure the space a circular rug covers or the cross-sectional area of a circular pipe. Knowing how to apply A = πr² is foundational in geometry, engineering, and architecture. Pairing this knowledge with circumference or volume formulas further expands your capability to handle circular shapes in diverse projects and daily scenarios.

Practice Questions

If a+b = 10 and ab = 21, what is the value of (a-b)^2?

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A sum triples in 20 years at simple interest. What is the rate of interest per annum?

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If the radius of a circle is doubled, what happens to its area?

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A man invests Rs. 5000 at 5% per annum simple interest. What is the total amount after 3 years?

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What is the area of a circle with a diameter of 14 cm?

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If x^3 - 3x^2 + 4 = 0, what is one root of the equation?

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If a:b = 7:9 and b:c = 5:6, what is a:c?

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What is the value of x if 3x + 7 = 16?

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What is the sum of the interior angles of a hexagon?

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A sum of money doubles itself in 5 years at simple interest. What is the rate of interest?

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