Triangle Angle-Sum Theorem & Exterior Angles
3-3 Parallel Lines & the Triangle Angle Sum
Theorem
M11.B.2 2.4.11.B
Objectives:
1)
To classify triangles and find the measures of their
angles.
2)
To use exterior angles of triangles.
Triangle Angle-Sum
The sum of the measures of the angles of
a triangle is 180.
m<A + m<B + m<C = 180
C
B
A
Example: Find the missing value
Find m<Z
Y
X
Z
48°
67°
Example: Find the missing value
Triangle ABC, <ACB is a right angle, and
CD AB. Find the values of a, b, and c
(Textbook page 133 - TE)
T
Ex: Find the value of x, y, and z.
(textbook page 132)
G
F J H
Classify Triangles: by Angles
Equiangular
Acute
Right
Obtuse
Classify Triangles: by Sides
Equilateral
Isosceles
Scalene
Ex: Classify a Triangle by its Angles & Sides
2
4
5
Vocab
An
exterior angle of a polygon
, is an angle
formed by a side and an extension of an
adjacent side.
For each exterior angle of a triangle, the
two nonadjacent interior angles are its
remote interior angles
.
Triangle Exterior Angle Theorem.
m<1= m<2 + m<3
Example: Using the Exterior Angle Theorem
The classification of triangles based on angles and sides, discover the Triangle Angle-Sum Theorem where the sum of angles in a triangle is 180 degrees, and understand the concept of exterior angles in triangles. Learn how to find missing angle values and classify triangles by angles and sides using real-life examples and explanations.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
You are allowed to download the files provided on this website for personal or commercial use, subject to the condition that they are used lawfully. All files are the property of their respective owners.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.
E N D
Presentation Transcript
3-3 Parallel Lines & the Triangle Angle Sum Theorem M11.B.2 2.4.11.B Objectives: 1) To classify triangles and find the measures of their angles. 2) To use exterior angles of triangles.
Triangle Angle-Sum The sum of the measures of the angles of a triangle is 180. m<A + m<B + m<C = 180 C A B
Example: Find the missing value Find m<Z Z 67 48 X Y
Example: Find the missing value Triangle ABC, <ACB is a right angle, and CD AB. Find the values of a, b, and c (Textbook page 133 - TE) T
Ex: Find the value of x, y, and z. (textbook page 132) G F J H
Classify Triangles: by Angles Equiangular Acute Right Obtuse
Classify Triangles: by Sides Equilateral Isosceles Scalene
Vocab An exterior angle of a polygon, is an angle formed by a side and an extension of an adjacent side. For each exterior angle of a triangle, the two nonadjacent interior angles are its remote interior angles. Triangle Exterior Angle Theorem. m<1= m<2 + m<3
