The difference between the circumference and the radius of a circle is 185 cm. Find the diameter of the circle.

Question: The difference between the circumference and the radius of a circle is 185 cm. Find the diameter of the circle.

Solution:
Let r be the radius of circle

Given that,
2πr - r = 185
⇒ r(2π - 1) = 185
⇒ r{(44/7) - 1} = 185
⇒ r (44 - 7)/7 }= 185
⇒ r(37/7) = 185
⇒ r = 185 (7/37)
∴ r = 35

The radius of the circle is 35 cm.
∴ Diameter = 2 × 35
= 70 cm