Lesson 9-6
Name each triangle below.
Objective - To classify triangles.
1)
Triangle Names
Angle
Name
3)
7
7
11
4
Right Scalene
Obtuse Isosceles
Acute - All angles Right - Only One Obtuse - Only One
less than 90 .
angle equal to 90 . angle more than 90 .
2)
Side
Name
4)
3
8
9
Equilateral - All
Isosceles - Two
three sides equal. sides equal.
Scalene - No
equal sides.
B
x
Obtuse Scalene
Acute Equilateral
Angle-Side Relationships
Angles opposite congruent sides are congruent.
Equilateral Triangles
A
5
3
m∠A = m∠B = m∠C = 180°
x
x
8
3x = 180°
3
3
x = 60°
C
7
60° 8
60° 60°
11
8
Acute Equilateral
Obtuse Isosceles
Sides opposite congruent angles are congruent.
All equilateral triangles must be acute.
30°, 30°, 120°
Obtuse Isosceles
Impossible Triangle Names
Right Equilateral
Obtuse Equilateral
Acute Equilateral Acute Isosceles
Use the diagram below to name the following.
Name each triangle below.
5)
B
7)
2
12
5
6)
5
13
8
Right Scalene
C
8
13
13
A
D
13
18
F
10
E
1) Acute Equilateral Triangle 3) Acute Isosceles Triangle
8)
6
Acute Isosceles
13
12
5
Acute Scalene
7
6
Obtuse Isosceles
+BCE
+BEF
2) Right Scalene Triangle
4) Obtuse Scalene Triangle
+ABF
+CDE
Math 6 Slide Show: Teaching Made Easy As Pi, by Mike Mills and James Wenk © 2011