Question

Find the perimeter of a circle whose radius is $7$ cm (in cm)
A.$12\pi $
B.$14\pi $
C.$16\pi $
D.$10\pi $

Answer 1

Hint: The perimeter of a circle is also known as the circumference of the circle and it is the measurement of the boundary of the circle. Perimeter of the circle is $ = 2\pi R$ where; R is the radius of the circle. Also, the parameters are given in centimetre and answer is required in the pie form. Generally, the term “circumference” is used for the circles.

Complete step by step solution-
Given that- Radius of the circle, $R = 7cm$
 Perimeter of the circle is $ = 2\pi R$
 Put values$R = 7cm$, $\pi = \dfrac{{22}}{7}$
 Perimeter of the circle is $ = 2 \times \dfrac{{22}}{7} \times 7$
  Simplify the above equation –
  [$7$ From the numerator and the denominator cancels each other]
  Perimeter of the circle is $ = 2 \times 22$
                                                 $ = 44cm$
The perimeter of a circle with radius is $7$ cm is $44$ cm.
Therefore, the required solution is - Perimeter of the circle is $ = 2\pi R$
 Perimeter of the circle is $ = 2\pi \times 7$
                                              $ = 14\pi $
Hence the perimeter of the circle is $ = 14\pi $
Therefore, from the given multiple choices, option B is the correct answer.


Note: Generally, the length of the straight sided shapes such as square, rectangle, triangles outlines is called its perimeter and the length of the circle’s outline or any arc’s such as semi-circle outline is called its circumference and $\pi $ is used in the formula whereas perimeter is sum of all the sides using additions. . Alternative method to find the perimeter of the circle $ = \pi D$, where D is the diameter of the circle. Always check the given units of the parameters and the required units of the solution.