# Understand Circle with Circle Formulas:

**circle formulas**provide a clear picture of its features and use after studying the

**definition of a circle**. This formulas can further be used to derive various properties of circle.

Consider c as the center point, r as the radius and d as the diameter of the circle shown below. Than the **formula for a circle** diameter is d = 2R, i.e. Diameter of a circle is twice that of its Radius.

**Let's see the formula for Circle Area & Volume:**

** **Archimedis was the first one to find the area of **a circle**. Later his theory was accompanied by many mathematicians. Based upon this theories, **Circle Area **is equal to πR^{2 }where R is the Radius & π being constant that approximates 3.1414. **Volume of a circle** in 3 dimensions is given by 4πR^{3 }/3. The **volume of circle **can actually be considered for that of a sphere.

**Learn Graphing a Circle on x-y axis:**

** Graphing a circle **on x-y axis is very easy. Only things required for this are radius and the center point of a circle. Suppose we want to graph a circle that has radius 5 with the center point of (4,4). Than locate the center point on the graph, measure the radius on the compass and draw the circle. Now according to **circle geometry**, equation of circle is (x-4)^{2} + (y-4)^{2 }= 5^{2}.

**Have a look at most important Circle Theorems:**

** Circle theorems **about Inscribed Angle states that inscribed angle a is equal to half of central angle as shown below.

**Formula to find Circle perimeter:**

** Circle perimeter** is defined as the linear distance of outside curve of circle. It's also known as Circumference. Perimeter of circle P = 2πR.

**Important properties of circles:**

** **Some of the important **properties of circles **are diameter, chord, tangent, secant, arc, sector and segment. We have already looked at diameter. So let's move on to rest. Chord is a line whose both endpoints lie on circle which makes diameter as the biggest chord. Tangent is a line that touches circle at particular point. Secant can be considered as an extended chord line. Arc can be considered as part of circle's circumference. Sector is the area bound by 2 radius and the arc covering them. Similarly segment is the region bound by chord and arc covering it. These properties helps to have complete study of circle.

## Video lesson on Unit Cirle

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