Download 2. - Net Start Class

8-5 Classifying
Insert Lesson
Title Here
Polygons
Learn to identify and name polygons.
Course 2
8-8 Angles in Polygons
Polygon A closed figure with 3 or more
straight sides that do not cross.
Course 2
8-5 Classifying Polygons
Determine whether each figure is a polygon. If it is not,
explain why not.
Course 2
8-8 Angles in Polygons
Regular Polygon A polygon with congruent sides
and angles.
Course 2
8-5 Classifying Polygons
Determine whether each figure is a regular polygon. If it is
not, explain why not.
Course 2
8-8 Angles in Polygons
Diagonal A straight line that joins two non-adjacent
vertices of a polygon.
Course 2
8-8 Angles in Polygons
Learn to find the measures of angles in
polygons.
Course 2
8-8 Angles in Polygons
Take the paper triangle on your desk
and name the corners 1, 2, and 3.
Carefully tear off two of the corners.
Rotate them so the straight edges meet
at the vertex and point in the same
direction as the un-torn corner.
You should find that they formed a straight angle.
This suggests that the sum of the measures of the
angles in a triangle is 180°.
Course 2
8-8 Angles in Polygons
Angles of a Triangle
The sum of the
measures of the
angles in a triangle
is 180°.
Course 2
2
1
3
m1 + m2 + m3 = 180°
8-8 Angles in Polygons
Remember this from 6th grade?
Angles
of a Quadrilateral
How many
degrees
are in a quadrilateral?
The sum of the
measures of the
angles in a
quadrilateral is
360°.
2
3
1
4
m1 + m2 + m3 + m4
= 360°
Course 2
8-8 Angles in Polygons
Course 2
8-8 Angles in Polygons
Number of sides
Skip this slide. For teacher use only
Name of figure
(Number of triangles) x 180o = Total interior degrees
Course 2
8-8 Angles in Polygons
3 sides
Triangle
(1)180o = 180o
Course 2
8-8 Angles in Polygons
4 sides
Quadrilateral
(2)180o = 360o
Course 2
8-8 Angles in Polygons
5 sides
Pentagon
(3)180o = 540o
Course 2
8-8 Angles in Polygons
6 sides
Hexagon
(4)180o = 720o
Course 2
8-8 Angles in Polygons
8 sides
Octagon
(6)180o = 1080o
Course 2
8-8 Angles in Polygons
(# of triangles)180 = total interior degrees
3 sides
4 sides
5 sides
(1)180° = 180 °
(2)180° = 360 °
(3)180° = 540 °
(4)180° = 720 °
6 sides
(6)180° = 1080 °
8 sides
50 sides (48)180° = 8640 °
n sides (n - 2)180°
Course 2
8-8 Angles in Polygons
Find the measure of the unknown angles.
1.
Course 2
2.
8-8 Angles in Polygons
Find the unknown angle measure in the
quadrilaterals.
4.
Course 2
5.
8-8 Angles in Polygons
Take out yesterday’s notes:
Course 2
8-6 Classifying Triangles
Classify each triangle according to its sides and angles.
C.
3 congruent sides
___
3 _______
acute angles
___
equilateral_______
acute triangle.
This is an________
D.
No congruent sides
___
1 obtuse
___
_____ angle
This is a _______
scalene obtuse
_____ triangle.
Course 2
8-6 Insert
Lesson
Title Here
Classifying
Triangles
Classify each triangle according to its sides and angles.
2 congruent sides
___
E.
1 _______
obtuse angles
___
isosceles _______
obtuse triangle.
This is an________
F.
2 congruent sides
___
1 _____
right angle
___
right triangle.
This is aisosceles
_______ _____
Course 2
8-6 Classifying Triangles
Identify the different types of triangles in the figure, and determine how
many of each there are.
Type
Course 2
How many
Name
Scalene
2
ABD,
BCD
Isosceles
2
ACE,
ABC
Right
2
ABD,
BCD
Obtuse
1
ACE
Acute
1
ABC
Math Humor
What did the girl have to use to get her
enormous collection of CD-Roms to her
friend’s house?
a CD-ROMbus!!!
8-8 Angles
Insert Lesson
in Polygons
Title Here
Lesson Quiz
Find the measure of the unknown angle for
each of the following.
1. a triangle with angle measures of 66° and 77°
37°
2. a right triangle with one angle measure of 36°
54°
3. an quadrilateral with angle measures of 144°,
84°, and 48°.
84°
4. Divide a six-sided polygon into triangles to
find the sum of its interior angles
720°
Course 2