Answer :
Perimeter = 2 × π × r
Perimeter = 2 × 3.14 × 9
Perimeter = 56.52
Perimeter = 56.52 ÷ 2
Perimeter = 28.26
The perimeter of a semicircle with a radius of 9mm is 28.26
Perimeter = 2 × 3.14 × 9
Perimeter = 56.52
Perimeter = 56.52 ÷ 2
Perimeter = 28.26
The perimeter of a semicircle with a radius of 9mm is 28.26
PI times diameter = 3.14 * ( 2*9mm) /2 = 28.27433388 mm this is the correct answer