Find perimeter of semicircle whose diameter is 43cm
Answers
The continuous closed line that makes the boundary of a two-dimensional shape is known as the perimeter. It’s easy to work out the perimeter of a shape with straight edges, such as a square, because you simply add the lengths of each edge together. A different formula is required to work out the perimeter of a semi circle (a circle cut in half), because it consists of a curved edge as well as a straight edge. That formula is
P = \frac{1}{2} πd + dP=
2
1
πd+d
where d is the diameter of the semi circle.
Apply the number pi (π) to the formula
P = \frac{1}{2} πd + dP=
2
1
πd+d
Pi is a circle's circumference divided by its diameter and is always the same value, 3.14.
To find the perimeter of a semi circle, you have to know the diameter (the length of its straight edge). For example, if the diameter of your semi circle is 12 centimeters, the formula becomes
P = \frac{1}{2} ×(3.14×12) + 12P=
2
1
×(3.14×12)+12
Work out
3.14 × 12 = 37.683.14×12=37.68
Then work out
37.68 ÷ 2 = 18.8437.68÷2=18.84
You now have the perimeter of the curved edge of the semi circle. But a semi circle also has a straight edge, which is why you have to add the length of the diameter to calculate the whole perimeter. In this case, work out
18.84 + 12 = 30.8418.84+12=30.84
The perimeter of your semi circle is 30.84 centimeters.