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
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