Question

Find the circumference of a circle whose radius is
(I)5.6 cm
(ii) 49 cm
(iii) 63 cm
(iv) 8.4 cm
(v) 4.2 cm​

Answer 1

Answer:

1. circumference of a circle = 2πr

so, 2×22/7 ×5.6 = 2×22×5.6/7 =

44×5.6/7 = 246.4/7 = 35.2cm

2. circumference of a circle = 2πr

so, 2×22/7×49

= 44×49/7 = 2156/7 = 308cm

3. circumference of a circle = 2πr

so, 2×22/7×63 = 2×22×63/7 = 44×63/7 = 2772/7 =

396cm

4. circumference of a circle = 2πr

so, 2×22/7×8.4 =2×22×8.4/7 = 44×8.4/ 7 =

369.6/7 = 52.8cm

5. circumference of a circle = 2πr

so, 2×22/7×4.2 = 2×22×4.2/7 = 44×4.2/7 = 184.8/7

26.4 cm .

hope it helps you

Answer 2

Given:-

• Radius of different circles

To find:-

• Circumference of each circle.

Solution:-

(i) 5.6 cm

⟶ Here radius = 5.6

We know,

• Circumference of the circle = 2πr

Hence,

Circumference = 2 × 22/7 × 5.6

⇒ Circumference = 2 × 22 × 0.8

⇒ Circumference = 44 × 0.8

⇒ Circumference = 35.2 cm

∴ Circumference of the circle is 35.2 cm

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(ii) 49 cm

⟶ Here radius = 49 cm

Hence,

Circumference = 2πr

⇒ Circumference = 2 × 22/7 × 49

⇒ Circumference = 2 × 22 × 7

⇒ Circumference = 44 × 7

⇒ Circumference = 308 cm

∴ Circumference of the circle is 308 cm

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(iii) 63 cm

⟶ Here radius = 63 cm

Hence,

Circumference = 2πr

⇒ Circumference = 2 × 22/7 × 63

⇒ Circumference = 2 × 22 × 9

⇒ Circumference = 44 × 9

⇒ Circumference = 396 cm

∴ Circumference of the circle is 396 cm

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(iv) 8.4 cm

⟶ Here radius = 8.4

Hence,

Circumference = 2πr

⇒ Circumference = 2 × 22/7 × 8.4

⇒ Circumference = 2 × 22 × 1.2

⇒ Circumference = 44 × 1.2

⇒ Circumference = 52.8 cm

∴ Circumference of the circle is 52.8 cm

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(v) 4.2 cm

⟶ Here radius = 4.2 cm

Hence,

Circumference = 2πr

⇒ Circumference = 2 × 22/7 × 4.2

⇒ Circumference = 2 × 22 × 0.6

⇒ Circumference = 44 × 0.6

⇒ Circumference = 26.4 cm

∴ Circumference of the circle is 26.4 cm

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