LEARN MATH STEP BY STEP THROUGH VERY EASY PROCESS

CIRCUMFERENCE & AREA OF A CIRCLE

**CIRCLE –**

**A circle is considered as the set of all
points in a plane that are considered at a constant distance from a fixed point
will be called the center of the circle. The constant
distance will be considered as the radius of the circle, and a diameter of a circle will be considered as twice of its radius.**

**Circumference of a Circle –**

**
The length of the entire arc of a circle will be called
its circumference. The ratio of the length of the circumference (C) to the
diameter (D) is considered as the same for all circles. We represent this ratio
by Pi and the symbol of the Pi is denoted by π.**

**Where, Circumference (C), Diameter (D)**

**So, **

**Circumference (C) : Diameter (D) = Pi (π)**

**So, C : D = π
**

** C**

**=> ------- = π , C = D
π [ where π = 22/7 = 3.1416 approx.
]**

** D**

**Since,
Diameter (D) = 2 X radius **

**So,
C = 2 πr**

__Area Of Circle –__

**The area of a circle is considered by
the measurement of the region bounded by the circle. The relationship between
the area (A) and the radius (r) of a circle is as follows.**

**A = πr²**

**Or,
r = √ A / π**

**There are some different formulas of
circles given below for calculation-**** 1**

**The area of a semicircular region of
radius (r) = ----- πr²**

** 2 **

**If the radii of two concentric circles
(considered as, circles with the same center) are r & R, r < R then**

**
**

**The area of the ring (or annulus) = πR² - πr²
**

** = π ( R² - r² ) **

** = π (R + r) (R – r) **