question_answer

Find the circumference of the circled with the following radius: \[\left( Take\,\pi \,=\frac{22}{7} \right)\]

(a) 14 cm

(b) 28 mm

(c) 21 cm

Answer:

We know that the circumference C of a circle of radius r is given by C =\[2\pi r\].

(a) Here, r = 14 cm

\[\therefore \]                 C = Circumference =\[2\pi r\]

\[=\left( 2\times \frac{22}{7}\times 14 \right)cm\]

= 88 cm

(b) Here, r = 28 mm

\[\therefore \]      C = Circumference = \[2\pi r\]

\[=2\times \frac{22}{7}\times 21\,\,cm\]

\[=2\times 22\times 3\,\,cm\]

= 132 cm

(c) Radius = 21 cm

Circumference = \[2\pi r\]

\[=23\times \frac{22}{7}\times 21\,\,cm\]

= 2 × 22 × 3 cm

= 132 cm