Download - Bombay Cambridge Gurukul
Bombay Cambridge GurukulSTD. : VI
Bombay Cambridge Gurukul
MATHEMATICS
Contents
• Angles in daily life
• What is an angle?
• Naming an angle
• Measurement of angle
• Types of angle: Right angle Obtuse angle Acute angleStraight angle
• Test Yourself - 1
• Congruent angles• Pairs of angles: Types
• Test Yourself - 2 • Pairs of angles
formed by a transversal
• Test Yourself - 3
If we look around us, we will see angles everywhere.
Angles In Daily Life
Common endpoint
B C
B
A
Ray BC
Ray BA
Ray BA and BC are two non-collinear rays
When two non-collinear rays join with a common endpoint (origin) an angle is formed.
What Is An Angle ?
Common endpoint is called the vertex of the angle. B is the vertex of ÐABC.
Ray BA and ray BC are called the arms of ÐABC.
Fact: We can also think of an angle formed by rotating one ray away from its initial position.
To name an angle, we name any point on one ray, then the vertex, and then any point on the other ray.
For example: ÐABC or ÐCBA
We may also name this angle only by the single letter of the vertex, for example ÐB.
A
BC
Naming An Angle
Angles are accurately measured in degrees.
Protractor is used to measure and draw angles.
Measurement Of An Angle
There are four main types of angles.
Straight angle
Right angle Acute angle Obtuse angle
A
B C
A
B C
A
B C
BA C
Types Of Angles
Right angle: An angle whose measure is 90 degrees.
Right Angle Acute AngleStraight Angle Obtuse Angle
Examples Of Right Angle
Obtuse angle: An angle whose measure is greater than 90 degrees.
Right Angle Acute AngleStraight Angle Obtuse Angle
Examples Of Obtuse Angle
Acute angle: An angle whose measure is less than 90 degrees.
Right Angle Acute AngleStraight Angle Obtuse Angle
Examples Of Acute Angle
Straight angle: An angle whose measure is 180 degrees.
Right Angle Acute AngleStraight Angle Obtuse Angle
Examples Of Straight Angle