That means the arc length of the semicircle is 1413 units. By transposing the above formula you solve for the radius central angle or arc length if you know any two of them. Finally multiply that number by 2 pi to find the arc length.
We know that for the angle equal to 360 degrees 2p the arc length is equal to circumference.
We know that for the angle equal to 360 degrees 2p the arc length is equal to circumference. Example 1 Find the arc length and area of a sector of a circle of radius 6 6 cm and the centre angle 2p 5 2 p 5. The length of an arc is found by forming a ratio of the arc to the whole circle then multiplying it by the formula for circumference either 2pr 2 p r or pd p d like this. Therefore if you divide an arcs degree measure by 360 you find the fraction of the circles circumference that the arc makes up.