Find the perimeter of the semi-circular lamina with the measurements given below.

Radius = 14cm

Diameter = 7cm

*Answers are given at the end of this article.

Perimeter of Quarter Circle

The arc length of the quarter circle

It is clear from the figure that, to find the perimeter of a quarter circle, two radii should add to the arc length.

The perimeter of quarter circle

Example 04:

If the radius is 28cm, find the perimeter of the quarter circle.

Therefore the perimeter of the quarter circle

= 44cm + 56cm

= 100cm

Perimeter of a Circle Sector

A region bounded by two radii and an arc is called a sector of a circle.

The angle subtended at the center of the circle by the arc is called the central angle.

Here the central angle is ‘θ‘

The angle at the center of the circle is 360^{o}. The arc length related to the 360^{o}angle is 2πr.

By looking at the above diagram we can say that,

For 360^{o} the arc length will be 2πr.

The arc length of a sector of a circle with radius ‘r’ and central angle ‘π‘.

Example 05:

Find the perimeter

Arc length is 11cm.

Therefore the perimeter of the sector

= 11cm + 2 x 9cm

= 11cm + 18cm

= 29cm

Answers

Exercise 01

Exercise 02

Calculator for Semi Circles - Area and Perimeter

Using this calculator, you can find the area and perimeter of semi-circles.

Radius, diameter, Perimeter and area calculation option are available. Select what you need to find and enter the number in text box. Then click ‘submit’.

Always remember this calculator is only checking for your answers. You have to do the exercises your self.

Chris OConnor….so E1Q3? You asked “Find the circumference of the circle with the measurements Diameter 1712cm” Am I right thinking that should have been d=17-1/2?

AdminYes Chris. It is 17 1/2.