Question

find the circumference of the circles with the following radii. (Take π = 22/7) a. 7 cm b. 21 cm c. 14 cm d. 7/2 cm​

Answer 1

Find the circumference of the circles with the following radii. (Take π = 22/7)

• a. 7 cm
• b. 21 cm
• c. 14 cm
• d. 7/2 cm

Formula used : Circumfrence = 2πr

Question A :

$\mathtt{c = 2\times \frac{22}{\cancel7} \times \cancel7} \\ \\ \implies\mathtt{2 \times 22 = 44 \: cm \: \: ans}$

Question B :

$\mathtt{c = 2\times \frac{22}{\cancel7} \times \cancel {21} } \\ \\ \implies\mathtt{44 \times 3= 132 \: cm \: \: ans}$

Question C :

$\mathtt{c = 2\times \frac{22}{\cancel7} \times \cancel {14} } \\ \\ \implies\mathtt{4 \times 22= 88 \: cm \: \: ans}$

Question D

$\mathtt{c = 2\times \frac{\cancel {22}}{\cancel7} \times \frac{\cancel {7}}{\cancel {2}} } \\ \\ \implies\mathtt{2 \times 11= 22 \: cm \: \: ans}$

Answer 2

Answer:

Given :-

• A circle whose radius are (a) 7 cm, (b) 21 cm, (c) 14 cm and (d) 7/2 cm.

To Find :-

• What is the circumference of the circle.

Solution :-

☆ (a) 7 cm :

Given :

• Radii = 7 cm

According to the question by using the formula we get,

$\implies \sf\boxed{\bold{Circumference_{(Circle)} =\: 2{\pi}r}}$

$\implies \sf Circumference_{(Circle)} =\: 2 \times \dfrac{22}{7} \times 7$

$\implies \sf Circumference_{(Circle)} =\: \dfrac{308}{7}$

$\implies \sf\bold{Circumference_{(Circle)} =\: 44\: cm}$

$\therefore$ The circumference of a circle is 44 cm .

☆ (b) 21 cm :

Given :

• Radii = 21 cm

According to the question by using the formula we get,

$\implies \sf\boxed{\bold{Circumference_{(Circle)} =\: 2{\pi}r}}$

$\implies \sf Circumference_{(Circle)} =\: 2 \times \dfrac{22}{7} \times 21$

$\implies \sf Circumference_{(Circle)} =\: \dfrac{924}{7}$

$\implies \sf\bold{Circumference_{(Circle)} =\: 132\: cm}$

$\therefore$ The circumference of a circle is 132 cm .

☆ (c) 14 cm :

Given :

• Radius = 14 cm

According to the question by using the formula we get,

$\implies \sf\boxed{\bold{Circumference_{(Circle)} =\: 2{\pi}r}}$

$\implies \sf Circumference_{(Circle)} =\: 2 \times \dfrac{22}{7} \times 14$

$\implies \sf Circumference_{(Circle)} =\: \dfrac{616}{7}$

$\implies \sf\bold{Circumference_{(Circle)} =\: 88\: cm}$

$\therefore$ The circumference of a circle is 88 cm .

☆ (d) 7/2 cm :

Given :

• Radius = 7/2 cm

According to the question by using the formula we get,

$\implies \sf\boxed{\bold{Circumference_{(Circle)} =\: 2{\pi}r}}$

$\implies \sf Circumference_{(Circle)} =\: 2 \times \dfrac{22}{7} \times \dfrac{7}{2}$

$\implies \sf Circumference_{(Circle)} =\: \dfrac{308}{14}$

$\implies \sf\bold{Circumference_{(Circle)} =\: 22\: cm}$

$\therefore$ The circumference of a circle is 22 cm .