Download Day 1 Classifying Triangles.notebook

Day 1 Classifying Triangles.notebook
Unit 2: Triangles
October 17, 2013
Day 1 Classifying Triangles.notebook
October 17, 2013
Vocabulary:
Polygon: a closed figure in a plane that is made up of segments that intersect only at their endpoints
Triangle: a 3­sided polygon
Parts of a Triangle:
Sides: Segments that make a triangle
Vertices: Points where sides meet
Day 1 Classifying Triangles.notebook
October 17, 2013
Triangles are named by using their three vertices. For example:
D
R
U
The name of this triangle is DUR. RUD
RDU
UDR
URD
DRU
We can classify triangles by the relationship between their sides.
Scalene: no congruent sides
Isosceles: 2 congruent sides
Equilateral: 3 congruent sides
Day 1 Classifying Triangles.notebook
October 17, 2013
Classify each triangle as equilateral, isosceles, or scalene.
7
7
12
5
4
10
7
4
We can also name triangles by the relationships between their angles.
Acute: 3 acute angles
Obtuse: 1 obtuse angle (2 acute)
Right: 1 right angle (2 acute)
(
Equiangular: 3 congruent angles
(
(
7
Day 1 Classifying Triangles.notebook
October 17, 2013
Classify each triangle as acute, obtuse, right, or equiangular. If it fits more than one, use both.
1.
2.
60
3.
60
30
60
30
60
4.
115 35
51
84
45
Right Triangles
Hypotenuse: Side opposite the right angle in a right triangle
Legs: the two sides that make up the right angle in a right triangle
Day 1 Classifying Triangles.notebook
October 17, 2013
True or False?
___a.) All isosceles triangles are acute.
___b.) An acute triangle can be equilateral.
___c.) A scalene triangle is never obtuse.
___d.) A right angle can be isosceles.
Example
Find the length of the sides.
A
4x­14
B
x+10
C
Day 1 Classifying Triangles.notebook
October 17, 2013
Example
2x+5
Find x.
31
Day 1 Classifying Triangles.notebook
October 17, 2013
Triangle Sum Theorem:
o
The sum of the angle measures of a triangle is 180.
Corollaries from Triangle Sum Theorem:
The acute angles of a right triangle are complementary.
1
o
m< 1 + m< 2 = 90
2
The measure of each angle of an equiangular triangle is 60.o
Day 1 Classifying Triangles.notebook
October 17, 2013
34o
Homework
pg. 227­229 (12­19,23­31,35­37,41­43)
pg. 235­237 (6­8,16­18, 29­32, 35)
Attachments
03 Wonderwall.m4a