Page 129 - ICSE Math 5
P. 129
The region between the two rays is called the interior of the angle and the region outside the two
rays is called the exterior of the angle.
An angle can also be defined as the amount of turning or rotation between two arms that have
a common vertex.
We see different angles in the surroundings all the time. Let’s look at the shape of some objects
that form angles.
Classifi cation of Angles
Angles are mainly of four types. Let’s know about the types of angles.
Right angle
An angle that measures 90° and is formed by a vertical line and a horizontal line is called a right
angle. Some examples of right angles that we see in our surroundings are shown below.
Mathematics
Acute angle
An angle that measures more than 0° and less than 90° is called an acute angle. Some examples
of acute angles that we see in our surroundings are shown below.
Obtuse angle
An angle that measures more than 90° and less than 180° is called an obtuse angle. Some
examples of obtuse angles that we see in our surroundings are shown below.
119
