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

The perimeter of a rectangle is 50 cm, and its length is 15 cm. What is its width?

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A car covers a distance of 150 km in 2.5 hours. What is its average speed?

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If x:y = 4:5 and y:z = 2:3, what is x:z?

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A number is increased by 20% and then decreased by 10%. What is the net change?

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If the angles of a triangle are in the ratio 2:3:4, what is the measure of the largest angle?

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

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If x = 3 and y = 4, what is the value of x^2 + y^2?

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

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If a cone has a base radius of 3 cm and height of 4 cm, what is its slant height?

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The sides of a triangle are 7, 24, and 25. Is this a right triangle?

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