A Large circle at the center, with various circular sectors, arcs, chords, and segments radiating outward from it.
CBSE 10

CBSE 10 Mensuration: Everything You Should Know about Circles (Detailed Formulas)

Aha
May 16, 2024

In this article, we will cover all the necessary information and provide detailed explanations to help you master this topic.

Introduction to areas related to circles

Areas related to circles is a crucial topic in mathematics that deals with finding the area of various shapes and figures that are based on circles. It is essential to understand the properties of circles and their parts to solve problems related to areas of circles.

Area of a circle

The area of a circle is the amount of space it occupies in a two-dimensional plane. The formula to calculate the area of a circle is given by:

Area of a circle = πr²

where r is the radius of the circle.

Circumference of a circle

The circumference of a circle is the distance around it. The formula to calculate the circumference of a circle is given by:

Circumference of a circle = 2πr

where r is the radius of the circle.

Angle of a sector

The angle of a sector of a circle is the angle formed by two radii and an arc. It is measured in degrees.

Sector of a circle

A sector of a circle is a part of the circle enclosed between two radii and an arc. The formula to calculate the area of a sector of a circle is given by:

Area of a sector of a circle = (θ/360)πr²

where θ is the angle of the sector in degrees and r is the radius of the circle.

Length of an arc of a sector

The length of an arc of a sector of a circle is the distance along the arc from one end to the other. The formula to calculate the length of an arc of a sector of a circle is given by:

Length of an Arc of a Sector = (θ/360)2πr

where θ is the angle of the sector in degrees and r is the radius of the circle.

Segment of a circle

A segment of a circle is a part of the circle that is enclosed between a chord and an arc. The formula to calculate the area of a segment of a circle is given by:

Area of a segment of a circle = (θ/360)πr² - (1/2)r²sin θ

where θ is the angle of the sector in degrees, r is the radius of the circle, and s is the length of the arc.

Area of a triangle

The area of a triangle can be calculated using the following formula:

Area of a triangle = (1/2)bh

where b is the base and h is the height.

Formulas list

Here is a list of all the formulas we have covered so far:

  • Area of a circle = πr²
  • Circumference of a circle = 2πr
  • Length of an arc of a sector = (θ/360)2πr
  • Area of a sector of a circle = (θ/360)πr²
  • Area of a segment of a circle = (θ/360)πr² - (1/2)r²sin(θ)
  • Area of a triangle = (1/2)bh

Areas of different plane figures

Areas of different plane figures can be calculated using various formulas. It is important to understand the properties of each figure and use the appropriate formula to calculate its area.

Areas of combination of plane figures

When two or more plane figures are combined, their areas can be calculated by adding or subtracting the areas of individual figures.

Practice questions

To master areas related to circles, it is essential to practice. Here are some example questions with step-by-step solutions:

Example 1:

Find the area of a circle with a radius of 5 cm.

✅  Solution: Area of a Circle = πr² = π(5)² cm² = 25π cm².

Example 2:

Find the area of a segment of a circle with a radius of 10 cm and an angle of 60 degrees.

✅  Solution: Area of a Segment of a Circle = (θ/360)πr² - (1/2)r²sin θ =
                          (60/360)π(10)² - (1/2)(10)²sin 60° cm² = 50/3π - 25√3 cm².

FAQs

What is the formula for calculating the area of a circle?

The formula for calculating the area of a circle is

Area of a Circle = πr²

where r is the radius of the circle.

What is the difference between circumference and perimeter?

Circumference is the distance around a circle, while perimeter refers to the total distance around any closed figure.

How do you calculate the length of an arc of a sector?

The formula to calculate the length of an arc of a sector is

Length of an Arc of a Sector = (θ/360)2πr

where θ is the angle of the sector in degrees and r is the radius of the circle.

What is the formula for calculating the area of a segment of a circle?

The formula for calculating the area of a segment of a circle is

Area of a Segment of a Circle = (θ/360)πr² - (1/2)r²sin θ

where θ is the angle of the sector in degrees, r is the radius of the circle, and s is the length of the arc.

Conclusion

Areas related to circles is a crucial topic in mathematics, and it is essential to understand the properties of circles and their parts to solve problems related to areas of circles. To further practice and improve your skills in mathematics, it is recommended checking out the website Aha AI.

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