This document provides definitions and examples of common mathematical symbols and terms used in an introductory math lesson. It defines angle symbols like ∠, parallel symbols like ‖, logical symbols like ∴ and ∵, ratio symbols like :, and the ellipsis symbol .... Examples are provided to illustrate the meaning and usage of each symbol in mathematical contexts such as geometry, proofs, and sets. The document appears to be notes for a math lesson prepared by an instructor named Sivar A. B.

1. 4th Lesson Introduction to Math.
Ishik University
∟‖ ∴… ∵ : ∠
Faculty of Education
Physics Department
Instructed and Prepared by: Sivar A. B.

2.  Used over an amount to show that this is an angle
 Example:
 A triangle of equal side with angle ∠ 60 of on of the
sides.

 Means that the angles ∠ ABC=∠CAB ∠BCA=30̊
∠ Degree
A B
C

3.  A triangle with one of the angles right , means that
 A =∟ Right angle =90 ̊ means ∠BAC= 90 ̊
∟ Right angle
A
B
C

4.  When two of the sides are parallel to each other
means the angle between these sides are zero degree
 *(0̊ )
 1- so A and D are parallel means that the angle
between them is zero degree (0̊ ) so A ‖ C, as well as
 B ‖ D
‖ Parallel to
A
B
C
D
z

5.  A : B means the Frobenius inner product of the
matrices A and B.
 A : B means the division of A with B (dividing A by B)
10 : 2 (ten to two) = 5
: Is to or ratio

6. ∴ therefore, so and hence
 Sometimes used in proofs before logical
consequences.
Example:
 A ‖ D and D ‖ E ∴ A ‖ E
A
B
C
D E

7.  Sometimes used in proofs before reasoning.
 Example:
 x + y = 6
 ∵ x =1
 ∴ x+y=1+y=6
 y= 6-1=5
∵ Since or Because

8.  An ellipsis is also often used in mathematics to mean
"and so forth". In a list, between commas, or
following a comma, a normal ellipsis is used, as in:
 1,2,3, …,100.
 N is a normal set of number
 N={0,1,2, …, ∞}
… ellipsis or etc.