Question

find the circumference of a circle whose diameter is (i) 21cm(ii) 10m (iii) 4.2 km

plzzz give full solution ​

Answer 1

Answer:

1) 66

2) 31.2

3)13.2

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Answer 2

1) Circumference Of Circle = 65.94 cm

2) Circumference Of circle = 31.4 m

3) Circumference Of circle = 13.188 km

Step-by-step explanation:

1)

GIVEN

Diameter = 21 cm

Radius = Diameter / 2 = 21 / 2 = 10.5cm

π = 3.14

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We know that

Circumference of circle = 2πr

Circumference of circle = 2 × 3.14 × 10.5

Circumference of circle = 6.28 × 10.5

Circumference of circle = 65.94

Circumference of circle = 65.94 cm

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2)

GIVEN

Diameter = 4.2 km

Radius = Diameter / 2 = 10 / 2 = m

π = 3.14

___________________________

We know that

Circumference of circle = 2πr

Circumference of circle = 2 × 3.14 × 5

Circumference of circle = 6.28 × 5

Circumference of circle = 31.4

Circumference of circle = 31.4 m

___________________________

3)

GIVEN

Diameter = 4.2 km

Radius = Diameter / 2 = 10 / 2 = 2.1 km

π = 3.14

___________________________

We know that

Circumference of circle = 2πr

Circumference of circle = 2 × 3.14 × 2

Circumference of circle = 6.28 × 2

Circumference of circle = 13.188

Circumference of circle = 13.188 km

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