Smart Math Formula Circle, A
circle is a certain distance from the point to the so-called rotating
circle, whose name is the diameter (d) is the diameter and the radius [ r
] is half of the diameter.

Wide circle = πr ²

Diameter of circle = 2r

Circumference of circle= 2πr= πd

Sector wide = πr x [θ/360]

Note :

Diameter of circle = 2r

Circumference of circle= 2πr= πd

Sector wide = πr x [θ/360]

Note :

**r = radius , d = diameter , ∏ = 3.14 or 22/7 [ if radius and diameter can divided 7 ]**### Example

Question : Find the area, diameter and circumference of a circle with the given radius 3.Answer: Find the area.

Area = πr² = 3.14 x 3² = 3.14 x 9 = 28.26.

Answer: Find the diameter.

Diameter = 2r = 2 x 3 = 6.

Answer: Find the circumference.

Circumference = πd = 3.14 x 6 = 18.84.

Question : Find the area of sector with the given radius 3 and theta 30.

Answer: Find the area.

Area =πr²(θ/360) = 3.14 x 3² x (30/360) = 3.14 x 9 0.083 = 2.35.

That is example will clearly illustrates how to calculate the Area, Diameter and Circumference of a Circle, Area of Sector with Smart Math Formula way.