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

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

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The area of an equilateral triangle with side length 6 cm is:

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If a square has a perimeter of 64 cm, what is its area?

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If the perimeter of a square is 36 cm, what is the length of its diagonal?

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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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What is the HCF of 48 and 180?

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If the ratio of two numbers is 3:5 and their HCF is 4, what are the numbers?

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What is the sum of all even numbers between 1 and 100?

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If sin(A) = 3/5 and cos(B) = 5/13, where A and B are acute angles, what is sin(A+B)?

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If x^2 - 6x + 9 = 0, what is the value of x?

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