Question

If the area of a circle is 154 cm2, then its perimeter is
(A) 11 cm (B) 22 cm (C) 44 cm (D) 55 cm

Answer 1

(C)44 is the answer 
 given area of circle=154
       ⇒area of circle=πr²
                             =22/7 ×7×7.
                             =154 
so radius of the circle=7cm
 perimeter of circle=2πr
                           =2 ×22/7×7
                           =44cm
⇒perimeter of the circle=44 cm.

Answer 2

Given:

Area of a circle = 154 cm²

To find:

Perimeter of a circle = ?

Stepwise solution:

• The perimeter of circle can be computed when area of circle is given. But we need to compute the radius of the circle for calculating the perimeter.
• Radius of circle can be found from the area of circle (given).

         Area of circle = πr²

         154 cm² = (22÷7) × r².  (∵ π = 22/7)

         r² = 154 × (7 ÷ 22)

         r² = 49

         r = √49

         r = 7 cm

• So, the radius of the circle = 7 cm

• Now to find the perimeter of the circle apply the following equation:

       Perimeter of circle = 2πr

       Perimeter of circle = 2 × (22÷7) × 7 cm

       Perimeter of circle = 2 × 22 cm

       Perimeter of circle = 44 cm

• Hence, the perimeter of circle is 44 cm (option c).