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This chapter focuses on applying proportions to determine similarity in triangles and parallel line segments. It includes definitions, postulates, and theorems related to similar polygons and triangle properties. Key concepts such as the Property of Proportions, characteristics of similar shapes, and midsegment theorems are covered. Students will learn how to solve problems involving ratios and determine triangle similarity, ensuring they have a strong foundation in geometry.
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Ch 9.Rev Learning Target: I will be able to use proportions to determine similarity and parallel line segments of a triangle. Standard: various Ch 9.1 thru 9.5Review
Ch 9.1 Concept
a b a b c d c d = = Ch 9.1 Theorem 9-1 Property of Proportions For any numbers a and c and any nonzero numbers b and d, if , then ad = bc. Likewise, if ad = bc, then Concept
Ch 9.1 Answers: 10) x = -15 9) x = 49 12) x = 4.5 11) x = ± 10
Ch 9.2 Definition of Similar Polygons Concept
Ch 9.2 Theorem 9-10 Concept
4 10 15 9 6 16 10 6 ≠ = Ch 9.2 15) not similar 16) PQRS~WXYZ Concept
Ch 9.2 Answers: 13) 5x + 8x + 10x = 276; x = 12; 10(12) = 120 14) 3x + 2x = 12; x = 2 ⅖; 3(2 ⅖) = 7⅕, 2(2 ⅖) = 4 ⅘
3 50 15 + 10 + 13 x = Ch 9.2 x = 633 ⅓ Concept
Ch 9.3 Postulate 9-1 Concept
Ch 9.3 9-2 9-3 Concept
Ch 9.3 not similar (shapes are not the same) IJK ~ HFG SSS Similarity not similar (angles are not congruent) TUV ~ TSR AA Similarity
Ch 9.4 Theorem 9-5 Concept
Ch 9.5 Theorem 9-6 Concept
240 200 8 18 4 x 5 12 10 x 300 x = = = Ch 9.4 x = 22.5 x = 9.6 x = 250 Concept
Ch 9.5 Theorem 9-7 Concept
Ch 9.5 (Justify your answer) IJ = 10.5 • Since FI = IG, then I is the midpoint. • Since FJ = JH, then J is the midpoint. • By definition, IJ is the midsegment. • By the Triangle Midsegment Theorem, IJ = ½ GH Concept