Quick Start Expectations
1. Come in and sit quietly.
2. Fill in planner and HWRS:
Textbook: CMP3 Grade 7 Unit: Shapes and Designs
p. 53-56 #3-11, 16 Challenge #23
3. Work on Warm-up
Warm-up Answers
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p. 45
Launch video 2.2
The sum of a
triangle’s angles
are 180 degrees –
when put together
they form a
straight line
The sum of a
quadrilateral’s
angles are 360
degrees .
(2*180)
Test Devon’s idea with an
irregular triangle and quadrilateral
of your own design.
Did you get the same results?
Yes, you get the same thing!
Triangles = 180 degrees
Quadrilaterals = 360 degrees
Triangle = 3 angles
Quadrilateral = 4 angles
3 angles = 180 degrees
4 angles = 360 degrees
Pentagons = 5 angles 5 angles = 540 degrees
Hexagons = 6 angles 6 angles = 720 degrees
The number of triangles formed will be
2 less than the number of sides of the polygon.
n – 2 = triangles inside the polygon
n – 2 = triangles inside the polygon
5 sides – 2 = 3 triangles x 180 = 540 °
4 – 2 = 2 x 180 = 360 °
6 – 2 = 4 x 180 = 720 °
S = 180 (n - 2)
A = 180 (n – 2)
n
or
or
S = 180n - 360
A = 180n – 360
n
A = 180 - 360
n
or
Yes, his method works!
S=
Homework
Textbook: CMP3 Grade 7
Unit: Shapes and Designs
p. 53 #3-11, 16 Challenge: 23