Enter the radius and total degrees of the rotation arc of the semi circle to calculate the area. Now divide by 2 to find the arc length of the semi circle. Either enter an exact answer in terms of 7 or use 314 for I and enter your answer as a decimal.
In general you can solve any arc length problem with ratios.
Since we need the perimeter of a semicircle instead of a full circle divide this by 2 since the arc length is half but then add the diameter which is two times the radius to account for the straight part across the bottom. Find an answer to your question Find the arc length of the semicircle. Now that is the circumference of the entire circle. This is going to be equal to eight pi.