**Online calculator for calculating the area of a circle.** There are two ways to calculate the area of a circle: through the radius and diameter of the circle. After choosing the calculation option, set the radius or diameter and click the "Calculate" button. Our calculator will display the result of calculating the area, as well as show a detailed solution with which you can see how the result was obtained.

A circle is a plane that is bounded by a circle.

## Answer or solution 1

The area of a circle is equal to the product of pi (the ratio of the circumference of a circle to its diameter is 3.14) by the radius squared. The formula for finding the area of a circle looks like this:

Therefore, to find the area of a semicircle, it is necessary to multiply pi by the radius squared and divide by two. The formula for finding the area of a semicircle is as follows:

### Instruction manual

**1.** Build a circle with a given radius. Designate its center as O. In order to obtain a semicircle, it is enough to draw a segment through this point to the intersection with the circle. This segment is the diameter of this circle and is equal to its two radii. Remember what a circle is and what a circle is. A circle is a line with all points at an identical distance from the center. A circle is a part of a plane bounded by this line.

**2.** Remember the circle area formula. It is equal to the square of the radius times the continuous exponent? Equal to 3.14. That is, the area of a circle is expressed by the formula S = R2 R2, where S is the area and R is the radius of the circle. Calculate the area of the semicircle. It is equal to half the area of the circle, i.e., S1 =? R2 / 2.

**3.** In the case when only the circumference is given to you under the conditions, first find the radius. The circumference is calculated by the formula P = 2? R. Accordingly, in order to detect the radius, you need to divide the circumference by a factor of two. It turns out the formula R = P / 2 ?.

**4.** A semicircle can also be represented as a sector. A sector is a part of a circle that is bounded by its two radii and an arc. The area of a sector is equal to the area of a circle times the ratio of the central angle to the full angle of the circle. That is, in this case it is expressed by the formula S =? * R2 * n ° / 360 °. The sector angle is famous, it is 180 °. Substituting its value, you again get the same formula - S1 =? R2 / 2.