Page 169 - New Medley 5 Semester 2

Thus, we can conclude that the circumference is approximately three times
the diameter. The symbol ‘’ means approximately equal to.

Therefore, circumference  3 × diameter

Example 4: Find the approximate circumference of a circle with
diameter 8 cm.

Solution: Given, diameter of a circle = 8 cm

We know that circumference  3 × diameter

 3 × 8 cm  24 cm

Thus, the approximate circumference of the circle is 24 cm.

Example 5: Find the approximate circumference of a circle with radius
3.5 cm.

Solution: Given, radius of a circle = 3.5 cm

So, diameter = 2 × radius = 2 × 3.5 cm = 7.0 cm

So, circumference  3 × diameter  3 × 7 cm  21 cm

Thus, the circumference of a circle with radius 3.5 cm is
approximately 21 cm.

Example 6 : Compute the approximate radius of a circle whose

circumference is 48 cm.

Solution: Given, circumference of a circle = 48 cm

We know that circumference  3 × diameter
  Diameter  circumference  3

 (48  3) cm  16 cm

Since radius is half of the diameter, therefore

1
Radius = × 16 cm = 8 cm
2

Thus, the approximate radius of the circle is 8 cm.

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