CIRCUMFERENCE: 

CIRCUMFERENCE: Is a distance around the circle or we can call as perimeter of circle. The important concept in this topic are

• Circumference, C, is the perimeter of a circle. 
• The diameter, d, is the distance across the circle through the centre. 
• The radius, r, is the distance from the centre to the circumference.
• Pi, the ratio of the circumference to the diameter, C ÷ d, is the same for any circle. The ratio pi is written as the Greek letter π. 
• The formula for the circumference of a circle is C = π × d C = 2 × π × r