- A semicircle is half of a circle and a quarter-circle is a quarter of a full circle
- 2 quarter-circles make a semicircle
- 2 semicircles make a full circle
- Calculate the perimeter of semicircles and quarter-circles by multiplying the
circumference of circle by 1/2 or 1/4. Calculate the area of semicircles and quarter-circles by multiplying the area of
circle by Meter or radius.- perimeter of semicircle = 1/2 x (π x diameter) + diameter
- perimeter of quarter-circle = 1/4 x ( π x diameter) +2r
- Calculate the area of semicircles and quarter-circles by multiplying the area of by 1/2 or 1/4.
- area of semicircle = 1/2 x πr²
- area of quarter-circle = 1/4 x πr²
Eg Find the perimeter and area of figure A and B below. ( Take π = 3.14 )
Perimeter = 1/2 x (3.14 x 30 ) + 30 = 77.1 cm
Radius = 30 ÷ 2 = 15 cm
Area = 1/2 x (2 x 3.14 x 3 x 3) = 7.065 cm²
Perimeter = 1/4 x ( 2 x 3.14 x 3 ) + 3 + 3 = 10.71 cm
Area = 1/4 x (3.14 x 3 x 3) = 7.065 cm²