1, the area of the semicircle = π× the square of the radius ÷2. Letter formula: s semicircle =πr? ÷2。

2. The circumference of a semicircle = π× radius+diameter. C semicircle =πr+2r.

Extended data:

1, using

A semicircle can be used to construct the arithmetic and geometric mean of two lengths using a ruler and compasses. If we make a semicircle with a diameter of a+ b, the length of the radius is the arithmetic average of A and B (because the radius is half the diameter). The geometric mean can be obtained by dividing the diameter into two sections with lengths A and B, and then connecting their same ends into a semicircle with a line segment perpendicular to the diameter.

2. Pi

Pi is an infinite cycle decimal, which is usually expressed by the letter π = 3. 14159265358932384626 ... When calculating, it is usually 3.14. We can say that the circumference of a circle is π times the diameter, or about 3. 14 times the diameter, but we can't directly say that the circumference of a circle is 3. 14 times the diameter.

References:

Baidu encyclopedia-semicircle