**Half**a

**circle called**a

**semi**-

**circle**(with or without a hyphen). semicircle noun. a

**half**of a

**circle**or of its circumference. [ODO]

**Half**a sphere (like an igloo) is a hemisphere (which I've not generally seen hyphenated).

Keeping this in consideration, what is the formula for semi circle?

In the case of a circle, the formula for area, A, is A = pi * r^2, where r is the circle's radius. Since we know that a semicircle is half of a circle, we can simply

**divide**that equation by two to calculate the area of a semicircle. So, the formula for the area of a semicircle is A = pi * r^2/2.What is the measure of an angle inscribed in a semicircle?

Proof: The intercepted arc for an

**angle inscribed in a semi-circle**is 180 degrees. Therefore the**measure**of the**angle**must be half of 180, or 90 degrees. In other words, the**angle**is a right**angle**.How do you work out semi circle area?

**Steps**

- Find the radius of the semi-circle. You'll need the radius to find the area of the semi-circle.
- Find the area of the full circle and divide it by two. The formula for finding the area of a full circle is πr
^{2}, where "r" represents the radius of the circle. - Remember to state your answer in square units.