2.3 Types of triangles
Triangles are classified into various types, using two different parameters - the lengths of their sides and the measure of their angles.
Length of the Side
Based on the lengths of their sides, triangles are classified into three categories.
-
Equilateral triangle : If the lengths
of all three sides of the triangle are equal, then it is called
an equilateral triangle. Figure 2.3 shows an equilateral triangle.
Figure 2.3
-
Isosceles triangle : If only two sides
of a triangle are equal in length, it is called as an
isosceles triangle. Figure 2.4 shows an isosceles triangle.
Figure 2.4
-
Scalene triangle : If all the sides of
a triangle have different lengths it is called a scalene triangle.
Figure 2.5 shows a scalene triangle.
Figure 2.5
Angles
-
Acute triangle : A triangle in which
all the angles are acute, ( i.e. < 900 ) is called
as an acute triangle. Figure 2.6 shows an acute triangle.
Figure 2.6
A special case of an acute triangle is when all
the three acute angles are equal. This D
is called an equiangular triangle. Figure 2.7 shows an equiangular
triangle.
Figure 2.7
Since the sum of all the angles of a triangle
is 1800, it can be said that each angle of an equiangular
triangle is 600 .
-
Obtuse triangle : A triangle in which
one of the angles is obtuse is called as an obtuse triangle.
Figure 2.8 shows an obtuse triangle.
Figure 2.8
Since the sum of all the angles of a triangle
is 1800 it can be said that the other two angles of
an obtuse triangle are acute.
-
Right Triangle : It is a triangle in
which one of the angles is a right angle. Figure 2.9 shows a
right triangle.
Figure 2.9
Since Ð
KJL is 900 it can be said that Ð
JKJL and Ð JLK are complementary.
In a right triangle the side opposite to the right angle is
called the hypotenuse.
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Index
2.1 Introduction
2.2 Sum Of The Angles Of A Triangle
2.3 Types of Triangles
2.4 Altitude, Median And Angle Bisector
2.5 Congruence Of Triangles
2.6 Sides Opposite Congruent Angles
Chapter 3
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