The question asks to calculate the area of a semicircle which is half a circle so the area of a semicircle is half the area of a circle.

**Area of a semicircle = area of circle/2 or area of a circle = 2* area of semicircle.**

The formula for the area of a circle is pi times the radius squared:

**Area of a semicircle = πr ^{2} /2**

The diameter is a straight line that runs through the center of the circle from one point on a circle to another. The radius is the line from the centre of the circle to any point on the circle.

Thus, the length of a radius is half the length of the diameter.

**Radius = diameter/2 or diameter = 2* radius.**

**Question:**

The diameter of the circle is given i.e.12 cm. To calculate the area of a semicircle we must calculate the area of a circle and divide it by 2. The area of a circle = πr^{2} but the radius is not given. However, it is half the diameter so r = 12 / 2 = 6 cm. Then use it to calculate the area of a circle which is 3.142 * 6 * 6 = 113.112 cm^{2}. We use cm^{2} as the unit as the radius is measured in cm and it is squared. Then simply divide the area of the circle by 2 to calculate the area of the semicircle i.e. 113.112 / 2 = 56. 556 cm^{2}.