Grade 7 Geometry: Area of Circles

Worked examples

Real problems from the practice worksheets, solved one step at a time.

1. Example 1

   A circle has a radius of 7 centimeters. What is its area, in square centimeters? Use 3.14 for π.

   1. The area of a circle is A = πr².
   2. A = 3.14 × 7² = 3.14 × 49 = 153.86 square centimeters.

   Answer: 153.86

2. Example 2

   A round pizza has a diameter of 18 inches. What is its area, in square inches? Use 3.14 for π.

   1. The area of a circle is A = πr².
   2. The radius is half the diameter: r = 18 ÷ 2 = 9.
   3. A = 3.14 × 9² = 3.14 × 81 = 254.34 square inches.

   Answer: 254.34

3. Example 3

   A round tabletop has a diameter of 8 feet. What is its area, in square feet? Use 3.14 for π.

   1. The area of a circle is A = πr².
   2. The radius is half the diameter: r = 8 ÷ 2 = 4.
   3. A = 3.14 × 4² = 3.14 × 16 = 50.24 square feet.

   Answer: 50.24