The perimeter of a semi-circle consists of the curved part (half of the circumference of a circle) and the straight diameter connecting the two ends of the curved part.
The circumference of a full circle is given by 2πr, where r is the circle radius. Since a semi-circle is half of a full circle, the curved part of the semi-circle would be half of the circumference, which is (1/2) * 2πr = πr.
To calculate the semi-circle perimeter, we need to add the straight diameter to the curved part. The diameter of the full circle is 2r, so the diameter of the half-circle is r. Therefore, the perimeter of the semi-circle is equal to the curved part (πr) plus the diameter (r), which gives a total perimeter of πr + r.
In simplified form, the semi-circle perimeter is (π + 1) * r.