lines and angles
DESCRIPTION
LINES AND ANGLES content: Introduction Basic terms and definitions Intersecting lines and Non-intersecting lines Perpendicular lines Angles Types of angles Parallel lines TransversalTRANSCRIPT
By-Supriya Negi
Class-IX CRoll No.-30
LINES AND ANGLES
IntroductionBasic terms and definitionsIntersecting lines and Non-intersecting
linesPerpendicular linesAnglesTypes of anglesParallel linesTransversal
CONTENT
• 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
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.
BASIC TERMS AND DEFINITIONS
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
Two lines that intersect each other to form a right angle are called parallel
lines.
PERPENDICULAR LINES
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• Vertically opposite angles
ANGLES
An angle whose measure is more than 0˚ but less than 90˚ is called an acute angle.
ACUTE ANGLE
EXAMPLES OF ACUTE ANGLES
An angle whose measure is equal to 90˚ is called a right angle.
RIGHT ANGLE
EXAMPLES OF RIGHT ANGLES
An angle whose measure is less than 180˚ but more than 90˚ is called an obtuse angle.
OBTUSE ANGLE
EXAMPLES OF OBTUSE ANGLES
An angle whose measure is equal to 180˚ is called a straight angle.
STRAIGHT ANGLES
EXAMPLES OF STRAIGHT ANGLES
An angle whose measure is more than 180˚ but less than 360˚ is called reflex angle.
REFLEX ANGLE
EXAMPLES OF REFLEX ANGLES
Angles which have one common arm and a common vertex and the uncommon arms are opposite to each other are called adjacent angles.
ADJACENT ANGLES
EXAMPLES OF ADJACENT ANGLES
Angle formed by a line intersecting a straight line is called a linear pair.
LINEAR PAIR OF ANGLES
EXAMPLES OF LINEAR PAIR
Angles formed by two intersecting lines such that the opposite angles are equal are called vertically opposite angles.
VERTICALLY OPPOSITE ANGLES
EXAMPLES OF VERTICALLY OPPOSITE ANGLES.
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.
PARALLEL LINES
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
CORRESPONDING ANGLES
ALTERNATE INTERIOR ANGLES
ALTERNATE EXTERIOR ANGLES
INTERIOR ANGLES ON THE SAME SIDES OF TRANSVERSAL
END OF PRESENTATION
Thank you for watching.