Explanation:
The area of a circle = pi r^2
d = 2r Divide by 2 to get the radius
r = d/2
The diameter = 2.8 cm
r = d/2
r = 2.8/2
r = 1.4
The area of the circle = pi * r^1
The area of the circle = 3.14 * 1.4^2
The area of the circle = 6.1544
But you are working with a semic circle
The area of a semicircle is 1/2 that of a circle
Area of semicircle = 1/2 6.1544 = 3.0772 =3.08 when rounded