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Geometry is the study of the shape of an object. The objects you see in everyday life, such as books, windows, buildings, bridges, stars, and so on can be described with the help of geometry. Geometry is composed of symbols, shapes, numbers, and variables. Here we will focus on the symbols used in geometry....Read MoreRead Less
Geometry is the branch of mathematics that describes the configuration of objects in terms of their shape, size, angle, and dimension. Geometry also defines the position of an object and its distance from a reference point.
Geometry is applied in various fields, including construction, interior designing, graphic designing, the orbit of the earth, planetary motion, and so on.
The calculations related to the motion of the sun, timings of the sunrise and the sunset are also based on geometry.
Geometry is broadly classified into two types:
Plane geometry deals with twodimensional figures like squares, circles, rectangles, triangles, and so on. Solid geometry, on the other hand, deals with the study of threedimensional shapes like cubes, cuboids, cylinders, cones, spheres, and so on.
Various signs are used to represent geometric figures or quantities. These signs are known as geometry symbols. Let us explore these symbols in detail:
S.NO  Geometry symbol  Symbol name  Meaning or Definition of the symbol  Example: 
1  .  Point  A dot represents a point. It is used to locate the position of an object.  Point A, point B 
2  \(\leftrightarrow\)  Infinite Line  A line connecting an infinite number of points and extending infinitely in both directions.  
3  —  Line segment  A line starting from one point, say ‘A’ and terminating at another point, say ‘B’. 

4  \(\rightarrow \)  Ray  Starts at one point and extends infinitely with no endpoint.  
5  ∠  Angle  Formed by the intersection of two rays.  \(\angle 1 = 20^{\circ},\) \(\angle {ABC}\)\(=110^{\circ},\) \(\angle A=40^{\circ}\) 
6  ∟  Right angle  Special angle which measures \( 90^{\circ}\).  ∟1 \( =90^{\circ}\). 
7  0  Degree  Unit of angle measure.  \(\angle 1 = 20^{\circ},\) \(\angle {ABC}\)\(=110^{\circ},\) \(\angle A=40^{\circ}\) 
8  \(\perp \)  Perpendicular  When two lines intersect at \(90^{\circ}\).  
9  \(\left  \right \)  Parallel  When two lines never intersect or the distance between them always remains the same.  AB CD 
10  ≅  Congruent to  Equivalence of geometric shape and size.  ∆ABC ≅∆XYZ 
11  ~  Similar to  Similarity in shape but not in size.  ∆ABC ~ ∆XYZ 
12  \(\neq \)  Not equal to  When two quantities are not equal.  If \(\angle A=40^{\circ},\) \(\angle B=0^{\circ},\) \(\angle A\neq \angle B\) 
13  I AB I  Absolute value  The distance between point A and point B.  
14  π  Pie, a constant term  The ratio of the circumference to the diameter of a circle.  π \(\approx \frac{22}{7}\approx 3.14\) 
15  Δ  Triangle  A polygon with three sides, three vertices, and three angles.  ΔABC 
16  Center of the circle 
Point A is the center of a circle  
17  Arc AB  The arc from point A to point B 
Example 1:
In the figure given below, two parallel lines are intersected by a transversal. Find the ∠B and ∠D.
Solution:
Since 40° and ∠D are alternate interior angles, they are congruent.
So, ∠D = 40°
Since 140° and ∠B are alternate interior angles, they are congruent.
So, ∠B = 140°
Hence, ∠D = 40° and ∠B = 140°.
Example 2: Compare  2.5  and \(\frac{3}{2}\).
Solution:
 2.5  = 2.5 [Absolute value]
\(\frac{3}{2}\) = 1.5 [Fraction to decimal]
2.5 > 1.5
So,
 2.5  > \(\frac{3}{2}\)
Example 3: Evaluate.  8 + 5 – \(\frac{4}{3}\) .
Solution:
8 + 5 – \(\frac{4}{3}\)
= – 3 – \(\frac{4}{3}\) [Simplify]
= \(\frac{ – 9 – 4}{3}\) [Simplify further]
= – \(\frac{13}{3}\)
So,  8 + 5 – \(\frac{4}{3}\)  =  – \(\frac{13}{3}\) [Absolute value]
Hence,  8 + 5 – \(\frac{4}{3}\)  = \(\frac{13}{3}\).
Example 4: In the triangle given below, find the measure of ∠C.
Solution:
In the given triangle, AB \(\perp\) BC, so ∠B = 90°.
∠A + ∠B + ∠C = 180° [Sum of angles of a triangle]
30° + 90° + C = 180° [Substitute values]
120° + C = 180° [Add]
C = 180° – 120° [Subtract 120 from both sides]
C = 60°
Hence, the measure of ∠C is 60°.
Symbols make it easier to refer to mathematical quantities and express the relationship between them. Symbols not only enhance understanding but also provide a universally perceivable way to represent certain math functions or illustrate a sequence.
A line is a collection of points and is extended in both directions infinitely. It has neither a start point nor an endpoint. The line AB passing through point A and point B extends to infinity in the right as well as in the left direction. The symbol of a line is
The line segment has two endpoints, and it does not extend infinitely in either direction. It is represented as
It may also be represented as
A ray is a line that has one endpoint and the other side of the line extends indefinitely. It is represented by one endpoint and the end by an arrowhead.
The ray originating from A and passing through B is represented as
The ray originating from B and passing through A is represented as
[Note: Ray is not same as ray ]