Examples
Ex 1:
The circumference of a circle of a radius 1.4 cm is
Sol:
| Put r = 1.4 cm in circumference = 2πr |
|
| = 44 ✗ 0.2 |
| = 8.8 cm |
Ex 2:
If the perimeter of a semicircle is 144 cm. Find its radius.
Sol:
| circumference + diameter = perimeter |
| πr + 2r = 144 cm |
|
Ex 3:
The moon is about 384000 km from the earth and its path around the earth is nearly circular. Find the circumference of the path described, by the moon in one complete revolution about the earth (π = 3.14).
Sol:
|
| Radius of the orbit = 384000 km |
| Distance covered = 2πr cm |
| = 2 ✗ 3.14 ✗ 384000 |
=
|
| = 628 ✗ 3840 |
| Distance covered in one complete revolution = 2411520 km |