Question

If the diameter of a circle is 21 cm, what will be its circumference?

Answer 1

Answer:

circumference is 66cm

Step-by-step explanation:

As the formula of circumference of a circle is 2pir

where r is the radius of the circle.

here, diameter is given ,ie 2r =21cm

put the values in the formula and use pi=22/7.

Hence, you will get your answer

Answer 2

Answer:

Answer is 65.97 (65.9734457) This is the Answer if you use the value of π is 3.14

Answer is 66 cm

This is the answer if you use the value of π is 22/7

Step-by-step explanation:

Diameter = 2 × r

Diameter = 2 × rcircumference = 2πr

Diameter = 2 × rcircumference = 2πr = π × diameter (2 × r(radius)

Diameter = 2 × rcircumference = 2πr = π × diameter (2 × r(radius)

= 65. 97

21 × 22/7

= 3 × 22

= 66