The perimeter or circumference of a circle = diameter times pi
Circumference ("perimeter") of a circle = (pi) x (diameter of the circle)
Multiply the diameter by pi.
Perimeter = pi*diameter = 113.1 cm
The equivalent of a "perimeter" in a circle is actually called its circumference. To get the diameter, just divide the circumference by pi.
Its perimeter is half of its circumference plus its diameter
You get 2 circles of diameter. If you were trying to find a perimeter, Never double the diameter. If you have a radius, You have to double it to get a perimeter.
First you have to measure the diameter of the circle. The diameter is pi (pi is approximately 3.1415) times the diameter is the perimeter. Half the diameter is the radius and the area of a circle is pi times the radius squared. So for example, let us say that you have a circle with a diameter of 3 inches. The perimeter is then about 9.42 inches, and the area is about 7.07 square inches.
Let r be the radius of the circle. Then the perimeter of the half circle is pi*r + 2r. That is half of the circumference plus the diameter.
Multiply its diameter by (pi), or its radius by (2 pi).
The perimeter of a circle is the circumference. If you mean the circle is drawn around (and touches the 4 corners of) a square, and you know the perimeter of the square, you divide the square's perimeter by 4, do pythagorean's theorem on the 2 sides (legs) to find the hypotenuse, and that hypotenuse will be the diameter of the circle. You then multiply that diameter you get by pi to get the circumference.
Pi times the diameter gives you the circumference. Then divide that answer by two. Then add in the diameter - and, voila, you have your answer as to the perimeter of a semicircle.