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 sin(θ) = 3/5 and θ is an acute angle, what is tan(θ)?

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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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A square is inscribed in a circle with a radius of 5 cm. What is the area of the square?

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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 a:b = 3:4 and b:c = 5:6, what is a:c?

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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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What is the square root of 144?

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If a right triangle has legs of 9 cm and 12 cm, what is the length of the hypotenuse?

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The perimeter of a rectangle is 40 cm, and its length is 12 cm. What is its width?

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What is the value of x if log(x) + log(4) = log(32)?

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