Geometric Shapes Lesson 1
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Transcript of Geometric Shapes Lesson 1
Geometric Shapes
Lesson 1
angles angles angles
Let’s Discover:Triangle Cut-Apart
What do you know about triangles?
Characteristics of triangle “angles”:
The sum of the angles in any size triangle is equal
to 1800.
90
55
35
90 + 35 + 55 = 180
Example 1:
80
45
x
Example 2:
Now try these:
In triangle ABC, m ∠ CAB = 57
and m ∠ ABC = 104. Find m ∠ ACB.
EXIT CARD:If you have angles 30 and 80 degrees, what is the
measure of the third angle?
Lesson 2
triangles triangles triangles
Brainpop Video
“Types of Triangles”
Characteristics of triangle “sides”:
The sum of the two smaller sides must be
greater than the length of the third side.
Example 1:
Can the following lengths make a triangle?
4 cm, 8 cm, 14 cm
4 + 8 = 12 12 ‹ 14 so no these sides cannot make a triangle.
Can the following lengths make a triangle?
5 in, 10 in, 13 in
Example 2:
5 + 10 = 15 15 › 13 so these sides do make a triangle.
Does the following lengths form a triangle?
a. 7 ft, 19 ft, 15 ft
b. 24 mm, 20 mm, 30 mm
c. 15 in, 25 in, 45 in
d. 4 cm, 12 cm, 18 cm
e. 1 yd, 10 yd, 20 yd
Exit Card:
3-2-1
Lesson 3http://www.youtube.com/watch?v=GO20ZgUzlc0
Let’s have some fun!!
IXL - Identify complementary, supplementary, vertical, adjacent, and congruent angles (8th grade math practice)
Exit Card:
One minute talk about differences in angle relationships with a
partner.
Lesson 4
Supplementary And
Complementary
How do you use supplementary angles to find unknown angle measures?
For Example
What is the measure angle x in the figure below?
110o xo
Let’s ReviewCore Lesson
A set of stairs inclines at a 110o angle. A support beam is going to be constructed under the stairs. What angle
measure does the support need to have?
110o
xo
Any interior ray from a point on a straight angle
creates two supplementary angles.
Let’s ReviewCore Lesson
110o
xo
110o + x = 180o
x = 70o
Supplementary angles add to 180o.
-110o -110o
Let’s ReviewCore Lesson
Two angles are supplementary. If one angle measure is 82o, what is the
measure of the second angle?
x + 82o = 180o
- 82o -82o
x = 98o
Let’s ReviewGuided Practice
Find the measure of angle x below.
158o xo
Let’s ReviewExtension Activities
Andy measured two angles. One angle was 153o and one angle was 47o. Andy said that the two angles were supplemental. Is Andy correct? Explain your reasoning.
How do you use complementary angles to find unknown angle measures?
For example
What is the measure of angle x?
xo
15o
Let’s ReviewLet’s Review
A right angle measures exactly 90o.
90o
Let’s ReviewCore Lesson
Two angles are complementary. If the measure of one angle is 43o, what is the measure of the second angle?
43o + x = 90o
-43o -43o
x = 47o43o
x
Let’s ReviewGuided Practice
Two angles are complementary. If one angle measures 17o, what is the measure of the second angle?
Let’s ReviewExtension Activities
Two angles are complementary. One angle measures xo and the second angle measures (x + 16)o. Find the measures of the two angles.
Let’s ReviewQuick Quiz
Two angles are complementary. One angle measures 22o. What is the measure of the second angle?
The two angles below are complementary. What is the measure of the missing angle?
63o
xo
Exit Card:
What is the difference in supplementary and
complementary angles?