Lesson 2 ­ Triangles ~ Does it make a Triangle ~ February 28.notebook
Warm­up: Under Tuesday on your answer sheet. February 28, 2017
Check IP:
Solve each inequality.
1. 24 + x > ­5
2. ­120 > ­10x
Feb 22­5:33 PM
Turn and Talk
Feb 22­5:44 PM
Spiral: 2/28 Triangle Side Lengths
Can the three lengths of the sides of a triangle be any three 2cm
???
6cm, 5
, 4c
numbers?
, 17cm
cm, 4
m
, 16cm
What do you know about triangles?
cm???
?
??
8cm?
5cm, 3cm, , 5c 12cm
m?
??
Let's see.........
Where have you seen them before?
You have a container with 4 different length straws.
copy into your spiral
green = 3cm ~ "g"
red = 5cm ~ "r"
forms a triangle does NOT form a triangle
blue = 7 cm ~ "b"
yellow = 9cm ~ "y"
Feb 24­10:59 AM
green = 3cm
forms a triangle does NOT form a triangle
red = 5cm
yellow = 9cm
Let's see........
3cm, 5cm, 9cm
3cm, 5cm, 7cm
9cm, 7cm, 3cm
Triangle Inequality:
The sum of any two sides of a triangle is greater than the length of the third side.
blue = 7 cm
5cm, 7cm, 9cm
Feb 22­5:50 PM
WHY???????
a + b > c
b + c > a
c + a > b
b
a
c
Can you write an inequality to explain WHY????
Feb 22­6:10 PM
Feb 9­7:28 AM
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Lesson 2 ­ Triangles ~ Does it make a Triangle ~ February 28.notebook
February 28, 2017
Triangle Inequality:
The sum of any two sides of a triangle is greater than the length of the third side.
4 + 5 > 7
4 + 2 < 7
4 + 7 > 5
4 + 7 > 2
7 + 5 > 4
2 + 7 > 4
What if.........
Can you give me a number that could represent the x? Is there only one possible answer?
9 ft
4 ft
x 11cm, 6cm, 13cm
5 ft, 15 ft, 9 ft
11 + 6 > 13
15 + 5 > 9
11 + 13 > 6
15 + 9 > 5
13 + 6 > 11
5 + 9 < 15
YES ~ these lengths could represent the shade: sides of a triangle.
NO ~ these lengths could represent the shade: sides of a triangle.
slide dowqn to reveal
slide dowqn to reveal
Feb 22­6:16 PM
Feb 22­6:40 PM
Exit Ticket 13 m
x
x
17 in
20 m
Explain how you know if three side lengths could make a triangle. 22 in
Which value(s) could be the length of x?
Which value(s) could be the length of x?
x = 29 in
x = 35 m x = 45 in
x = 13 m
https://www.youtube.com/watch?
v=7PfLSEpPQns&index=3&list=FL6gL6DLJsqEFza9ZVZJFdOA
Feb 22­6:45 PM
Feb 28­7:52 AM
IP: pg 427 (7­10 all) & Weekly Review
Mini­Assessment Review Feb 27­4:27 PM
Feb 22­6:55 PM
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