Important Concepts and Formulas
1. The Greek letter π
is defined as the ratio of the circumference to the diameter.
Circumference = Ï€ × diameter
= Ï€ × 2r (where r is the radius
of the circle)
= 2Ï€r
2. The area of a circle = πr2
To know the formulas for areas of different 2D shapes
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3. The length of an arc of a sector of a
circle with radius r and with central angle θ is given by:
4. Area
of a sector of a circle with radius r and with central angle θ is given by:
5. Area
of segment of a circle = Area of the corresponding circle – Area of the
corresponding triangle.