Smart Math Formula Circle
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 :
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.