Download isosceles triangle - Jefferson School District

9-6 Classifying Triangles
California
Standards
Preparation for MG2.3 Draw
quadrilaterals and triangles from given
information about them (e.g., a
quadrilateral having equal sides but no right
angles, a right isosceles triangle.)
Holt CA Course 1
9-6 Classifying Triangles
Vocabulary
scalene triangle
isosceles triangle
equilateral triangle
acute triangle
obtuse triangle
right triangle
Holt CA Course 1
9-6 Classifying Triangles
One way to classify triangles is by the lengths of
their sides.
Triangles classified by sides
A scalene triangle
has no congruent sides.
Holt CA Course 1
9-6 Classifying Triangles
One way to classify triangles is by the lengths of
their sides.
Triangles classified by sides
An isosceles triangle
has at least 2 congruent sides.
Holt CA Course 1
9-6 Classifying Triangles
One way to classify triangles is by the lengths of
their sides.
Triangles classified by sides
In an equilateral triangle, all of the
sides are congruent.
Holt CA Course 1
9-6 Classifying Triangles
One way to classify triangles is by the lengths of
their sides. Another way is by the measures of
their angles.
Triangles classified by angles
In an acute triangle, all of the
angles are acute.
Holt CA Course 1
9-6 Classifying Triangles
One way to classify triangles is by the lengths of
their sides. Another way is by the measures of
their angles.
Triangles classified by angles
An obtuse triangle has
one obtuse angle.
Holt CA Course 1
9-6 Classifying Triangles
One way to classify triangles is by the lengths of
their sides. Another way is by the measures of
their angles.
Triangles classified by angles
A right triangle
has exactly one right angle.
Holt CA Course 1
9-6 Classifying Triangles
Additional Example 1: Classifying Triangles
Classify each triangle according to its sides
and angles.
A. isosceles Two congruent sides
acute
Three acute angles
This is an isosceles acute triangle.
B. scalene
right
No congruent sides
One right angle
This is a scalene right triangle.
Holt CA Course 1
9-6 Classifying Triangles
Additional Example 1: Classifying Triangles
Classify each triangle according to its sides
and angles.
C. equilateral Three congruent sides
acute
Three acute angles
This is an equilateral acute triangle.
D. scalene
right
No congruent sides
One right angle
This is a scalene right triangle.
Holt CA Course 1
9-6 Classifying Triangles
Check It Out! Example 1
Classify each triangle according to its sides
and angles.
A. isosceles Two congruent sides
obtuse
One obtuse angle
This is an isosceles obtuse triangle.
B. isosceles
right
Two congruent sides
One right angle
This is an isosceles right triangle.
Holt CA Course 1
9-6 Classifying Triangles
Check It Out! Example 1
Classify each triangle according to its sides
and angles.
C. scalene
obtuse
No congruent sides
One angle exceeding 90°
This is a scalene obtuse triangle.
D. scalene
obtuse
No congruent sides
One angle exceeding 90°
This is a scalene obtuse triangle.
Holt CA Course 1
9-6 Classifying Triangles
Additional Example 2: Identifying Triangles
Identify the different types of triangles in the figure,
and determine how many of each there are.
Holt CA Course 1
Type
How many
Name
Scalene
2
ABD,
CBD
Isosceles
2
ACE,
ABC
Right
2
ABD,
CBD
Obtuse
1
ACE
Acute
1
ABC
9-6 Classifying Triangles
Check It Out! Example 2
Identify the different types of triangles in the
figure, and determine how many of each there
are.
A
I
B
J
C
D
H
G
Type
Isosceles
5
Name
DJA,
JDG
HJI,
BCD
DFE
F
Holt CA Course 1
How many
E
Obtuse
2
DJA,
ADG
Acute
4
JDG,
JHI,
BCD,
DEF