If the difference between the circumference and diameter

Home » Aptitude » Mensuration » Question

If the difference between the circumference and diameter of a circle is 30 cm, then the radius of the circle must be

Using Rule 14,
Let the radius of the circle be r cm.
Then, 2πr – 2r = 30
2r (π – 1) = 30

⇒ 2r ×	22 - 7	= 30
	7

⇒ 2r ×15 = 30 × 7 ⇒ r =	30 × 7	⇒ r = 7 cm
	30