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Geometry 7.2. SWLT: Use Proportions to identify similar polygons. Similar Polygons. Two or more polygons are similar, if corresponding angles are congruent and corresponding side lengths are proportional Same as when comparing and proving congruency, order is important. ABC DEF.
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Geometry 7.2 SWLT: Use Proportions to identify similar polygons
Similar Polygons • Two or more polygons are similar, if corresponding angles are congruent and corresponding side lengths are proportional • Same as when comparing and proving congruency, order is important.
ABC DEF • List all pairs of Congruent Angles A D, B E, C F • Confirm that the ratios of the corresponding side lengths are equal. • Write the ratios of the corresponding side lengths in a statement of proportionality B 8 10 A 12 C E 12 15 F D 18
BCD RST, Find the value of x • Write a Proportion • Substitute • Cross Multiply • Solve for x C 12 13 S 12x = 13(24) 12x = 312 x = 26 D B 5 24 x R 10 T
8 K L Theorem: Areas of Similar Polygons A = 24 • If two polygons are similar, then the ratio of their areas areequal to the ratios of their corresponding sides. • If KLMN PQRS, then… • 15(8) = 24PQ • 120 = 24PQ • PQ = 5 N M P Q A = 15 S R