The circle
The The distance around a shape. of a semi circle is the distance round the outside.
A semicircle has two edges. One is half of a circumference and the other is a diameter.
\(C = \pi d\)
\(= 3.14 \times 8\)
\(= 25.12cm\)
Remember this is the circumference of the whole circle, so now we need to half this answer.
\(25.12 \div 2 = 12.56cm\)
Total perimeter \(= 12.56 + 8 = 20.56cm\)
Area of a circle
For any circle with radius, r, the area, A, is found using the formula:
\(A = \pi {r^2}\)
\(A = \pi {r^2}\)
\(= 3.14 \times 12 \times 12\)
\(= 452.16c{m^2}\)
The area of a semicircle
A semicircle is just half of a circle. To find the Area is the measurement of the amount of space inside a surface. of a semicircle we calculate the area of the whole circle and then half the answer.
\(A = \pi {r^2}\)
\(= 3.14 \times 4 \times 4\)
\(= 50.24c{m^2}\)
Area of semicircle \(= 50.24 \div 2 = 25.12c{m^2}\)
The area of a combined shape
This shape is made up of a rectangle and a semicircle.
To find the total area we just find the area of each part and add them together.
Area of the rectangle = length x breadth
\(= 20 \times 30\)
\(= 600m{m^2}\)
\(Area\,of\,circle = \pi {r^2}\)
\(= 3.14 \times 10 \times 10\)
\(= 314m{m^2}\)
\(Area\,of\,semicircle = 314 \div 2 = 157m{m^2}\)
\(Total\,area = 600 + 157\)
\(= 757m{m^2}\)
