Formula for circumference that involves the radius ⇒ C = 2πr
Since we are given that the circumference is 86 cm, substitute it in.
86 = 2πr
Now, π is equal to approximately 3.14 so we can
plug 3.14 in for π and we have 86 cm = 2(3.14)r.
Now solve the equation.
2(3.14) is 6.28 and we have 86 cm = 6.28r.
Now divide both sides by 6.28 and we have 13.6942 = r.
So the radius of the hula hoop is 13.6942 cm.