__Angle:__**In geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.**

Picture of an Angle |

**Angle is also used to designate the measure of an angle or of a rotation. This measure is the ratio of the length of a circular arc by its radius. In the case of an angle (figure), the arc is centered at the vertex and delimited by the sides. In the case of a rotation, the arc is centered at the center of the rotation and delimited by any point and its image by the rotation.**

__Protractor:__**In geometry, a protractor is a square, circular or semicircular tool, typically in transparent perspex, for measuring angles. The units of measurement utilized are usually degrees (°).**

Picture of Protractor |

**They are used for a variety of mechanical and engineering-related applications, but perhaps the most common use is in geometry lessons in schools.**

__Drawing a Angle with Protector and Pencil:__Animation Showing Draw a Angle with Protector and Pencil.

Draw a line Base Ray of an Angle |

__Acute Angle:__

**Angle which is smaller than right angle or 90 degrees known as acute angle Example: angles from 1 degrees to 89 degrees**

Right Angle |

__Right Angle:__

**Angle which is equal to 90 degrees known as right angle Example: angles from 90 degrees.**

__Obtuse Angle:__**Angle which is greater than 90 degrees but smaller than 180 degrees known as obtuse angle Example: angles from 91degrees to 179 degrees**

__Straight Angle:__

**Angle which is equal to 180 degrees known as straight angle Example: angle of 180 degrees**

__Reflex Angle:__**Angle which is greater than 180 degrees but smaller than 360 degrees ,known as reflex angle Example: angle from 180 degrees to 359 degrees**

Complete Angle |

__Complete Angle:__**Angle which is equal to 360 degrees ,known as complete angle Example: angle of 360 degrees .**

__Triangles:__**A triangle is one of the basic shapes of geometry: a polygon with three corners or vertices and three sides or edges which are line segments. A triangle with vertices A, B, and C is denoted \triangle ABC.**

__Division of Triangle on the basis of length of Sides__

__1) Equilateral Triangle__

__2) Isoscales Triangle__

**Triangle having only two sides are equal in length.**

__3)Scalene Triangle__

**Triangle having all sides are unequal in length.**

**Animation showing**

**Division of different Triangle on the basis of length of Sides**

__1) Acute Angle Triangle__

**Triangle having angles of all three side are acute (less than 90 degrees) .**

__2) Obtuse Angle Triangle__

**Triangle having angle of one side is obtuse angle ( more than 90 degrees) .**

__3) Right Angle Triangle__

**Triangle having angles of one side is right angle ( 90 degrees) .**

**Animation showing**

**Division of different Triangle on the basis of different Angles.**

I think at the time math is very difficult subject, parents should help kids in solving math problems. and about 12 sided I want to share a simple definition as-12 sided polygon is called as dodecagon, This is one type of regular polygons, it may be regular or irregular. It’s a 12 sided closed figure.

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