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HW-pg. 465-466 (2-21) 7-1 to 7-3 Quiz THURSDAY 1-16-14 www.westex.org HS, Teacher Website 1-13-14 Warm up—Geometry H Decide if the pair of triangles look congruent or similar. 1. 2. What is the difference between two figures being congruent or similar? Today’s Goal I will be able to: 1. identify similar polygons. 2. apply properties of similar polygons to solve problems. HW-pg. 465-466 (2-21) 7-1 to 7-3 Quiz THURSDAY 1-16-14 www.westex.org HS, Teacher Website Name _________________________ Geometry H 7.2 Ratio & Proportion Today’s Goal I will be able to: 1. identify similar polygons. 2. apply properties of similar polygons to solve problems. Date ________ Figures that are similar (~) have the same shape but not necessarily the same size. Example 1: Describing Similar Polygons Identify the pairs of congruent angles and corresponding sides. YOU TRY: Identify the pairs of congruent angles and corresponding sides. A similarity ratio is the ratio of the lengths of the corresponding sides of two similar polygons. The similarity ratio of ∆ABC to ∆DEF is , or . The similarity ratio of ∆DEF to 2 ∆ABC is , or . 1 Example 2: Identifying Similar Polygons Determine whether the polygons are similar. If so, write the similarity ratio and a similarity statement. A. rectangles ABCD and EFGH B. ∆PQR and ∆STW YOU TRY: Determine if ∆LMJ ~ ∆PNS. If so, write the similarity ratio and a similarity statement. Example 3: Hobby Application Find the length of the model to the nearest tenth of a centimeter. YOU TRY: A boxcar has the dimensions shown. A model of the boxcar is 1.25 in. wide. Find the length of the model. 7.2 Practice 1. Determine whether the polygons are similar. If so, write the similarity ratio and a similarity statement. 2. The ratio of a model sailboat’s dimensions to the actual boat’s dimensions is . If the length of the model is 10 inches, what is the length of the actual sailboat in feet? 3. Tell whether the following statement is sometimes, always, or never true. Two equilateral triangles are similar.
