Download 3.6 - Classifying Triangles (and 3.7).notebook

3.6 ­ Classifying Triangles (and 3.7).notebook
November 17, 2014
3.6 ­ Classifying Triangles
Bellringer: Can the following sides make a triangle? Explain?
4, 7, 12
Can the following angles make a triangle? Explain?
Classifying Triangles by Side Lengths
• Scalene Triangle = No congruent sides
• Isosceles Triangle = At least 2 congruent sides
• Equilateral Triangle = All 3 sides congruent
45, 70, 80
Nov 17­12:31 PM
Sep 29­9:06 AM
3.6 ­ Classifying Triangles (Cont.)
Classifying Triangles by Angle Measures
• Acute Triangle = 3 acute angles
• Right Triangle = 1 right angle
• Obtuse Triangle = 1 obtuse angle
• Equiangular Triangle = All 3 angles congruent
Sep 29­9:06 AM
Sep 29­9:06 AM
3.6 ­ Classifying Triangles (Cont.)
3.7 (Cont.)
Type of Triangles in proofs
Thm: If two sides of a triangle are not congruent, then the angles opposite the sides are not congruent.
Extension:
Larger angle Larger side
and
Def: Isosceles Triangle ­­> 2 sides congruent
Smaller angle Smaller side
A
Leg
Leg
5
Base
Sep 29­9:06 AM
B
6
7
C
Sep 29­9:06 AM
1
3.6 ­ Classifying Triangles (and 3.7).notebook
November 17, 2014
3.6 Homework ­ Problem #11
Example
V
Given:GiveTriangle ABC has a perimeter of 34. Determine what type of triangle we have: scalene, isosceles, or equilateral. A
S
B
C
Sep 29­9:06 AM
Y
• Triangle VSY Isosceles
• Perimeter < 45
Sep 29­9:06 AM
2