<span>So we want to know what is a perimeter of a semicircle whos radius is 6cm. So to find the perimeter we can use the formula for the circle and divide that in half. Because the semicircle is exactly one half of a circle. So the formula for the perimeter for a circle is O=2r*pi and for the semicircle is one half of that: O=r*pi=6*3.14=18.84cm.</span>
