# RS Aggarwal Class 6 Math Twenty-one Chapter Concept Of Perimeter And Area Exercise 21B Solution

## EXERCISE 21B

CIRCUMFERENCE OF A CIRCLEThe perimeter of a circle is called its circumference.

Circumference = 2πr units

(1) Find the circumference of a circle whose radius is

(2) Find the circumference of a circle whose diameter is

(3) Find the radius of a circle whose circumference is 176 cm.

Solution: Let the radius of the circle is r cm.

(4) Find the diameter of a wheel whose circumference is 264 cm.

Solution: Let the diameter is d cm.

(5) Find the distance covered by the wheel of a car in 500 revolutions if the diameter of the wheel is 77 cm.

In revolution, the wheel covers a distance equal to its circumference.

So, distance covered by the wheel in 1 revolution = 2.42 m

And, distance covered by the wheel in 500 revolution = (2.42 x 500) m = 1210 m

(6) The diameter of the wheel of a car is 70 cm. How many revolutions will it make to travel 1.65 km?

Updated: May 30, 2022 — 12:46 pm