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Similar Figures. Using Proportions To Solve For Missing Sides. Definition of Similar Figures. To Shapes are similar if: Every Corresponding Angle is Congruent Every Corresponding Side is Proportional. ABCD ~ WXYZ. Example 1. W. A. m. 6. B. X. 7. 21. n. D. 15. C. 9. Z.
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Similar Figures Using Proportions To Solve For Missing Sides
Definition of Similar Figures To Shapes are similar if: Every Corresponding Angle is Congruent Every Corresponding Side is Proportional
ABCD ~ WXYZ Example 1 W A m 6 B X 7 21 n D 15 C 9 Z If you are given 2 shapes are similar then you can use proportions to Find missing values p Y
ABCD ~ WXYZ Example 1 W A m 6 B X 7 21 n D 15 C 9 Z Since 7 and 21 are corresponding sides and we know each value, we can use the ratio to solve for all the missing sides p Y
Use the sides that correspond to each other to set up equal proportions Example 1 ABCD ~ WXYZ W A m 6 B X 7 21 n D 15 C 9 Z p Y = = =
Now solve each proportion Example 1 = 7m = 126 Cross Multiply m = 18 Division Property
Now solve each proportion Example 1 = 7n = 105 Cross Multiply n = 15 Division Property
Now solve each proportion Example 1 = 7p = 189 Cross Multiply p = 27 Division Property
Often the Ratios do not Simplify nicely… In this case either leave answer as a fraction or make it a decimal Example 2 H E EFG ~ HIJ 9 x y 6 J G 16 12 F I Begin by using the ratio which reduces to
Use the corresponding sides to set up the proportions Example 2 H E EFG ~ HIJ 9 x y 6 J G 16 12 F I = =
Now solve each proportion Example 2 = 4x = 27 Cross Multiply x = 6.75 Division Property
Now solve each proportion Example 2 = 3y = 24 Cross Multiply y 8 Division Property