To find the perimeter, known as circumference, of a circle, the formula is C=πd. Since this is a semicircle, just divide it by 2. 4 times 3.14 is 12.56, divided by 2 is 6.28. The formula for the area of a circle is A=πr^2. The radius of this circle is 2, obviously. 2 times 2 is four. four times 3.14 is 12.56, divided by 2 is 6.28 units squared.
Circumference= 6.28 units
Area= 6.28 units squared