Insert Lesson Title Here Course 2 8-5 Classifying Polygons Insert Lesson Title Here Learn to identify and name polygons.

Polygon - 8-8 Angles in Polygons Course 2 8-8 Angles in Polygons Polygon - A closed figure with 3 or more straight sides that do not cross.

8-5 Classifying Polygons Course 2 8-5 Classifying Polygons Determine whether each figure is a polygon. If it is not, explain why not.

Regular Polygon - 8-8 Angles in Polygons Course 2 8-8 Angles in Polygons Regular Polygon - A polygon with congruent sides and angles.

8-5 Classifying Polygons Course 2 8-5 Classifying Polygons Determine whether each figure is a regular polygon. If it is not, explain why not.

Diagonal - 8-8 Angles in Polygons 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°.

8-8 Angles in Polygons Angles of a Triangle Course 2 8-8 Angles in Polygons Angles of a Triangle The sum of the measures of the angles in a triangle is 180°. m1 + m2 + m3 = 180° 2 1 3

Remember this from 6th grade? How many degrees are in a quadrilateral? Course 2 8-8 Angles in Polygons Remember this from 6th grade? How many degrees are in a quadrilateral? Angles of a Quadrilateral The sum of the measures of the angles in a quadrilateral is 360°. m1 + m2 + m3 + m4 = 360° 1 2 4 3

Course 2 8-8 Angles in Polygons Let’s Triangulate!

8-8 Angles in Polygons Number of sides 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

Noticing any pattern yet??? Course 2 8-8 Angles in Polygons (# of triangles)180 = total interior degrees 3 sides 4 sides 5 sides 6 sides 8 sides 50 sides n sides (1)180° = 180 ° Noticing any pattern yet??? (2)180° = 360 ° (3)180° = 540 ° (4)180° = 720 ° (6)180° = 1080 ° (48)180° = 8640 ° (n - 2)180°

8-8 Angles in Polygons Find the measure of the unknown angles. 1. 2. Course 2 8-8 Angles in Polygons Find the measure of the unknown angles. 1. 2.

Course 2 8-8 Angles in Polygons Find the unknown angle measure in the quadrilaterals. 4. 5.

Course 2 8-8 Angles in Polygons Take out yesterday’s notes:

Classifying Triangles Course 2 8-6 Classifying Triangles Classify each triangle according to its sides and angles. 3 C. ___ congruent sides ___ _______ angles 3 acute This is an________ _______ triangle. equilateral acute D. ___ congruent sides No obtuse ___ _____ angle 1 This is a _______ _____ triangle. scalene obtuse

Insert Lesson Title Here Course 2 8-6 Classifying Triangles Insert Lesson Title Here Classify each triangle according to its sides and angles. 2 ___ congruent sides E. ___ _______ angles 1 obtuse This is an________ _______ triangle. isosceles obtuse F. ___ congruent sides 2 1 right ___ _____ angle This is a _______ _____ triangle. isosceles right

Classifying Triangles Course 2 8-6 Classifying Triangles Identify the different types of triangles in the figure, and determine how many of each there are. Type 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!!!

Insert Lesson Title Here Course 2 8-8 Angles in Polygons Insert Lesson 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°