Classifying Triangles

1
Classifying Triangles

• Lesson One
• Unit Four
• Standards G 1, 3.4

2
Bellringer

• Refer to the figure
• Name a pair of consecutive interior angles.
• If m AB, name a pair of congruent angles and
  state why they are congruent.
• If m AB, name a pair of supplementary angles
  and state why they are supplementary.
• If AB represents the x axis and AC represents
  the y axis, is the slope of CB positive,
  negative, zero, or undefined?

7
12
3
Classifying Triangles

• Go through 4 1 of your text, Classifying
  Triangles.
• On a piece of notebook paper, state the headings,
  subheadings, note the pictures in the book, read
  the first paragraph, and the last paragraph, look
  at the examples, and state the bold words and
  their definitions.

4
What is a triangle?

• A three sided polygon
• What is a polygon?
• A closed figure in a plane that is made up of
  segments.
• What are those segments called?
• Sides
• Where do the sides intersect?
• Vertices
• There are three sides, three vertices, and three
  angles in a triangle.

5
Create a chart

• Create a chart or diagram of the triangle
  classifications. The chart should include the
  name of each type of triangle, a brief
  description, and a drawing.

6
Classifying Triangles by their angles
7
Acute Triangle

• An acute triangle is a triangle in which all
  three angles are acute.

60
48
72
8
Obtuse Triangle

• An obtuse triangle is a triangle in which one
  angle is obtuse and the other two are acute.

30
104
46
9
Right Triangle

• A right triangle is a triangle in which one angle
  in a right angle and the other two are acute.

51
39
10
Equiangular Triangle

• An equiangular triangle is a triangle in which
  all three angles are equal.

60
60
60
11
Classifying Triangles by their sides
12
Scalene Triangle

• A scalene triangle is a triangle in which all the
  sides have different measures.

11
8
4
13
Isosceles Triangle

• An isosceles triangle is a triangle in which at
  least two of the sides have the same measure.

7
7
3
14
Equilateral Triangle

• An equilateral triangle is a triangle in which
  all the sides have the same measure.

5
5
5
15
Parts of the ISOSCELES TRIANGLE
16
Picture
Vertex angle
leg
leg
Base angle
Base angle
base
Isosceles Triangles!
17
Parts of the RIGHT TRIANGLE
18
Picture!
hypotenuse
leg
leg
Right angle
19
How do we use this information?

• We use it to solve problems that involve the
  types of triangles discussed by using the
  properties. We can find this in architecture and
  in crafts.

20
Example 2
21
Example 3
22
Classwork

• Pg. 183 1 4, 11 15

23
Homework

• Pg. 184 16 23 and 30 45