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Radius and diameter of a circle. Radius : The radius is a line segment with one end point at the centre and the other end on the circle. It is denoted by ‘r’. Diameter : Diameter is a chord passing through the centre of the circle. It is denoted by ‘d’. r. A. O. O. B. A. d.
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Radius : The radius is a line segment with one end point at the centre and the other end on the circle. It is denoted by ‘r’. Diameter : Diameter is a chord passing through the centre of the circle. It is denoted by ‘d’. r A O O B A d
Relationship between diameter and radius: Diameter of a circle is twice of its radius. Formula: • Diameter = 2 x radius • Radius = r O r B A d
Pi (π) The ratio of circumference to diameter is constant for all circles. This ratio is called Pi and is written as π. Where π= C ⇒ = π ⇒ C = πd C = 2πr d 22 7
Example 1 : Find out the Diameter of a circle whose radius is 5 m. Solution Given:- radius(r)= 5 To Find:- diameter(d) Diameter of a circle (d) = 2 x radius = 2 x 5 = 10m (ans) Example 2 : Find out the Diameter of a circle whose radius is 24 m. Solution Given:- radius(r)= 24 m To Find:- diameter(d) Diameter of a circle (d) = 2 x radius = 2 x 24 = 48 m (ans)
Example 3 : Find out the radius of a circle whose diameter is 8 m. Solution Given:- diameter(d) = 8 To Find:- radius(r) Example 4 : Find out the radius of a circle whose diameter is 36 m. Solution Given:- diameter(d) = 36 m To Find:- radius(r)
Try these • Find out the radius of a circle whose diameter is 63 cm. • Find out the Diameter of a circle whose radius is 11 m.