Similar Polygons Geometry 8 2 Similar Figures Same

Similar Polygons Geometry 8 -2

• Similar Figures – Same shape but not necessarily the same size Vocabulary

• Get your supplies - Patty Paper - Ruler - Handout Similarity Exploration

• Use Patty paper to compare all the angles • How do the corresponding angles compare? • They are congruent Similarity Exploration

• Measure the corresponding segments in each polygon – Use metric • Find the ratios of the corresponding sides • (Small Side)/(Large Side) Similarity Exploration

• What did you learn about the ratios of the sides? Similarity Exploration

• Two polygons are similar if and only if the corresponding angles are congruent and the corresponding sides are proportional • Similar polygons are shown as follows Similar Polygons

• Two polygons are similar if and only if the corresponding angles are congruent and the corresponding sides are proportional Note: For similar polygons you must have BOTH congruent angles and proportional sides Similar Polygons

Example

Example

Example

Example

Example

Practice

Practice

Practice

Practice

Practice

Practice

Practice

Practice

Practice

Practice

Similar Polygons

• Get your supplies - Patty Paper - Ruler - Graph Paper Similarity Exploration

• Copy this figure onto your own graph paper • Pick one of the following scale factors ½ , ¾ , 2, 3 Similarity Exploration

• Multiply the coordinate of each of the vertices by your scale factor Similarity Exploration

• Plot each of these new points • The scale factor is the dilation of your figure Similarity Exploration

• Compare the lengths of the sides • How do these ratios compare to the scale factor? Similarity Exploration

• If one polygon is a dilated image of another polygon, then the two polygons are similar Dilation Similarity

SAMPLE PROBLEMS

• Pages 425 – 428 • 7, 8, 9, 11, 15, 18, 21, 23, 27, 33 Homework

• Pages 425 – 428 • 7, 8, 9, 11, 15, 18, 21, 23, 27, 33, 52 Honors Homework