The perimeter of a semicircle is 10.28 miles. What is the semicircle's diameter?

Use 3.14 for .

Answer: a semicircle is half the perimeter (or circumference) of its full circle, so the full circle here has a circumference of 20.56

Use that to figure out the length of the radius: Circumference divided by 2 (pi) will give you the radius.

Once you have the radius, use the formula for Area of a Circle: A = pi * radius2.

Once you have the area of the circle, divide that by 2 to get the area of the semicircle.

π=3.14 C=3.14 x 8cm C=25.1cm Divide by 2 for the semicircle 12.5 Add the diameter (8cm) 12.55+8=20.5