Math CC 78 Be Prepared On Desk Pencileraser

Math CC 7/8 – Be Prepared On Desk: Pencil/eraser HWTS HW from last night In Your Planner: In Your Journal: SD 2. 2 Angle Sums of any Polygon HW: SD p. 53 #3 -11, 16, 23 HW: AN UNIT TEST Corrections due Friday! Quiz – Fri. 10/12! AN Unit Test Retake-Fri. Oct. 19 th, in class

Tasks for Today • Go over a few questions on AN Test – 10 minutes • SD 2. 2 Angle Sums of ANY Angle • Begin HW?

p. 45 Launch video 2. 2?

First identify your triangle: right, acute, obtuse How do you know what it is? Share your triangle and why you know that. (Acute, all three triangles are acute. ) What others are the same. Challenge: Why does an acute angle have all acute angles? What about the obtuse angles? Can you draw a triangle with all obtuse angles? Why not?

Tear the corners of your triangle and connect the three vertices (like a puzzle). What do you notice? Does it form a benchmark angle? Compare with someone else who has the same triangle. What do you notice? Compare with someone else who has a different triangle. What do you notice?

Yes! Does this experiment with tearing corners work with other regular and irregular polygons? For a pentagon, the sum is 3 x 180 For a hexagon, the sum is 4 x 180

Handout foldable: First column: Divide the polygons into triangles, drawing from vertex to vertex. What do you discover? What relationship do you see between the number of sides and the number of triangles? What formula does this match?

The number of triangles formed will be 2 less than the number of sides of the polygon. n – 2 triangles

Yes, his method works! S=

Handout foldable: Second column: Draw a dot in the center of the polygon. Draw lines to each vertex to create triangles. What do you discover? What relationship do you see between the number of sides and the number of triangles? Draw a circle around the dot. What formula does this match?

S=

Discuss… don’t draw. Pentagons = 5 angles 3 angles = 180 degrees 4 angles = 360 degrees 5 angles = 540 degrees Hexagons = 6 angles 3 angles = 180 degrees 4 angles = 360 degrees 5 angles = 540 degrees 6 angles = 720 degrees