The document introduces basic concepts related to lines and angles, including definitions of intersecting, non-intersecting, perpendicular lines, and various types of angles like acute, right, and obtuse. It also explains the properties of parallel lines and transversals, highlighting the relationships formed by angles when lines intersect. Overall, the content emphasizes the importance of understanding these concepts in both everyday life and scientific contexts.

1. By-
Supriya Negi
Class-IX C
Roll No.-30
LINES AND ANGLES

2. Introduction
Basic terms and definitions
Intersecting lines and Non-intersecting
lines
Perpendicular lines
Angles
Types of angles
Parallel lines
Transversal
CONTENT

3. • In our daily life, we see different types of
angles formed between the edges of plane
surfaces. For making a similar kind of model
using the plane surfaces, we need to have a
thorough knowledge of angles.
• In science, we study the properties of light
by drawing the ray diagrams. For example, to
study the refraction property of light when
it enters from one medium to the other
medium, we see the properties of
intersecting lines and parallel lines.
INTRODUCTION

4. LINES : A straight path extending in both
directions with no end points.
LINE SEGMENT : A part of a line that
includes two points, called end points, and all
the points between them.
RAY : A part of a line, with one end point,
that continues without end in one direction.
BASICTERMS AND DEFINITIONS

5. INTERSECTING LINES : Lines that
cross each other.
NON – INTERSECTING LINES : Lines
that never cross each other and are
always parallel to each other.
INTERSECTING LINES AND NON-INTERSECTING LINES

6. Two lines that intersect each other to
form a right angle are called parallel
lines.
PERPENDICULAR LINES

7. Angle is formed when two rays originate from the
same end point. The rays making an angle are called
the arms of the angle and the end point is called the
vertex of the angle. There are many types of angles
such as :
• Acute angle
• Right angle
• Obtuse angle
• Straight angle
• Reflex angle
• Adjacent angles
• Linear pair of angles
ANGLES

8. An angle whose measure is more
than 0˚ but less than 90˚ is called
an acute angle.
ACUTE ANGLE

9. EXAMPLES OF ACUTE ANGLES

10. An angle whose measure is equal to 90˚
is called a right angle.
RIGHT ANGLE

11. EXAMPLES OF RIGHT ANGLES

12. An angle whose measure is less than 180˚
but more than 90˚ is called an obtuse
angle.
OBTUSE ANGLE

13. EXAMPLES OF OBTUSE ANGLES

14. An angle whose measure is equal to 180˚
is called a straight angle.
STRAIGHT ANGLES

15. EXAMPLES OF STRAIGHT ANGLES

16. An angle whose measure is more than
180˚ but less than 360˚ is called reflex
angle.
REFLEXANGLE

17. EXAMPLES OF REFLEX ANGLES

18. Angles which have one common arm and a
common vertex and the uncommon arms
are opposite to each other are called
adjacent angles.
ADJACENTANGLES

19. EXAMPLES OF ADJACENT ANGLES

20. Angle formed by a line intersecting a
straight line is called a linear pair.
LINEARPAIR OF ANGLES

21. EXAMPLES OF LINEAR PAIR

22. Angles formed by two intersecting lines
such that the opposite angles are equal
are called vertically opposite angles.
VERTICALLY OPPOSITE ANGLES

23. EXAMPLES OF VERTICALLY OPPOSITE ANGLES.

24. Parallel lines are the lines that remain
the same distance apart over their
entire length. No matter how far we
extend them, they will never meet.
PARALLELLINES

25. A transversal is a line that intersects two or more
parallel lines at different points.
There are some pair of angles formed when a
transversal intersects two lines such as :
 Corresponding angles
 Alternate interior angles
 Alternate exterior angles
 Interior angles on the same sides of
transversal
TRANSVERSAL

26. CORRESPONDING ANGLES

27. ALTERNATE INTERIORANGLES

28. ALTERNATE EXTERIOR ANGLES

29. INTERIOR ANGLES ON THE SAME SIDES OF TRANSVERSAL

30. END OF PRESENTATION
Thank you for watching.