Question

Difficulty: EasyPerimeter and Area of Plane Shapes

A circle has a circumference of 44 cm44\text{ cm}. What is the area of the circle? (Take π=227\pi = \frac{22}{7})

  1. 154 cm2154\text{ cm}^2Answer
  2. B
    308 cm2308\text{ cm}^2
  3. C
    616 cm2616\text{ cm}^2
  4. D
    44 cm244\text{ cm}^2

Answer

The area of the circle is 154 cm2154\text{ cm}^2.
First, find the radius from the circumference: C=2πr    44=2×227×r    r=7 cmC = 2\pi r \implies 44 = 2 \times \frac{22}{7} \times r \implies r = 7\text{ cm}. Then compute the area: A=πr2=227×72=154 cm2A = \pi r^2 = \frac{22}{7} \times 7^2 = 154\text{ cm}^2. Therefore, the value 154 cm2154\text{ cm}^2 is correct.

Step-by-Step Solution

1
Calculate the radius of the circle using the circumference formula
r=7 cmr = 7\text{ cm}
The formula for circumference is C=2πrC = 2\pi r. Substituting C=44C = 44 and π=227\pi = \frac{22}{7} yields 44=2×227×r44 = 2 \times \frac{22}{7} \times r, which simplifies to 447r=44\frac{44}{7}r = 44, so r=7 cmr = 7\text{ cm}.
2
Calculate the area using the area formula for a circle
Area = 154 cm2154\text{ cm}^2
The area formula is A=πr2A = \pi r^2. Substituting r=7r = 7 and π=227\pi = \frac{22}{7} gives A=227×72=22×7=154 cm2A = \frac{22}{7} \times 7^2 = 22 \times 7 = 154\text{ cm}^2.

Key Concept

Relationship between circumference and area of a circle
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