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# GEOMETRY

Basic Geometry in 6th grade is science deals with points, lines, curves, shapes, distances, angles, sides, degrees etc. of each and every object or building or structures we see in our day to day life.

Here we shall discuss about the basic understanding of things to enable us study different shapes and complicated arrangements using numbers at later stage.

Basic Geometry includes the following

1. Points
2. Lines
3. Line segments
4. Rays
5. Curves
6. Shapes
7. Sides
8. Angles

Point – Point is nothing but a small dot. This is similar to full stop that we use after completing a sentence……………………  Just for understanding i had used many dots after the word sentence.

#### Types of Lines in geometry –

Line – Line is something as shown here below and is continuous and can be of any length but is straight.

Intersecting Lines – when two lines cross each other or intersect, they are called intersecting lines.

Best example is alphabet  “X”.

Parallel Lines – When two lines never cross or intersect each other, they are parallel lines.

Example is number II.

Line Segment –  Segment means a portion of something. This is indicated by two points on the line and the line in between these two points is line segment.

Ray –  Ray is a line with one point or one end and it is continuous at other end.

Best example are sun rays … Starts at point and rays continuous indefinitely.

Curves – Any thing drawn which is not straight is called a curve. Any random shape

Example – Umbrella

##### Shapes : –

All the regular shapes which we learnt are geometric shapes. To name a few

1. Circle
2. Square
3. Rectangle
4. Square

From the above shapes we can observe the following

• circle has no sides and have no line segments.
• Square has 4 sides or 4 faces and all sides are line segments and are equal.
• Rectangle has 4 sides and all sides are line segments and only any two sides are equal.
• Triangle has 3 sides and all sides are line segments.
• A shape with 4 sides and all are unequal is called Quadrilateral.

Angle :- Angle is relation between two line segments in geometry and is measured in degrees.

Please refer angle is marked in the figure of rectangle. If we study the figure we can note the following

• Rectangle is made of 4 line segments  i.e AB , BC , CD and DA
• Line segments AB BC CD and DA are 4 sides of rectangle.
• AB and CD are equal (since two sides of rectangle are equal)
• Similarly AD and BC are equal (Since two sides of rectangle are equal)
• There are 4 angles at the intersection of line segments.
• 1 angle is marked and denoted as ADC in above rectangle figure means always the angle is at D which is intersection of rays AD and CD.

#### Measurement of angles

From the above figure we can infer or rather say that both square and rectangle has 4    angles and all are 90 degree angles at 4 corners.

A triangle has 3 angles they can be any 60:60:60, or may be 30:60:90 or may be any angle but the confirmation is always the sum of 3 angles in a triangle is 180 degrees.

Types of triangles based on sides

Equilateral triangle :-  A triangle which has all equal sides (length of side).

Isosceles triangle : – A triangle which has two equal sides.

Scalene Triangle : – A triangle which has all sides unequal.

## POLYGON

Polygon is a closed shape with 3 or more than 3 sides. We saw some above like square, triangle and rectangle. Lets see some more geometry shapes

Quadrilateral :- Quadrilateral is a a shape with four sides . We know square and rectangular shapes which are quadrilateral. Another 3 are here below

1. Rhombus
2. Trapezium
3. Parallelogram

How to recognize them ??

Note : – Shapes can also be defined by the number of sides it has

• Triangle has 3 sides
• Square and rectangle has 4 sides.
• Pentagon has 5 sides
• Hexagon has 6 sides
• Heptagon has 7 sides
• Octagon has 8 sides
• Nonagon has 9 sides
• Decagon has 10 sides

Till now we have seen shapes in 2 dimensions i.e length and width i.e two sides.

Lets learn 3 dimension shapes, the best example is Dice which has dots on all faces from 1 to 6.