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Comparison of two quantities by division Written as: a/b a : b a to b Always write in simplest form (reduced form) Make sure units of measure are the same

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Students will be able to write and solve ratios Students will be able to write and solve proportions Comparison of two quantities by division Written as: a/b a : b a to b Always write in simplest form (reduced form) Make sure units of measure are the same A bonsai tree 18 in wide and stands 2 ft tall. What is the ratio of the width compared to the height? First covert measurements to either inches or feet Then write the ratio in simplest form 18 : 24 3 : 4 A pigmy rattlesnake has average length of 18 inches, while a Western diamondback rattlesnake averages 5ft. 6in. What is the ratio of the length of a pigmy to a Western diamondback rattlesnake? 18 : 66 3 : 11 The measures of two supplementary angles are in the ratio 1:4. What are the measures of the angles? Write the ratio in words: angle 1 angle 2 Then write using variables: x 4x Set up an equation: x + 4x = 180 Solve the equation: x = 36 Substitute x back into the ratio Angle 1 = 1(36) = 36 Angle 2 = 4(36) = 144 The measures of two complementary angles are in the ratio 1:3. What are the measures of the angles? Write the ratio in words: angle 1 angle 2 Then write using variables: x 3x Set up an equation: x + 3x = 90 Solve the equation: x = 22.5 Substitute x back into the ratio Angle 1 = 1(22.5) = 22.5 Angle 2 = 3(22.5) = 67.5 Compares 3 or more numbers Written as a : b : c The lengths of the sides of a triangle are in the extended ratio 4 : 7 : 9. The perimeter is 60 cm. What are the lengths of the sides? Write an equation: 4x + 7x + 9x = 60 Solve for x: x = 3 So the lengths of the sides are: 4(3) = 12 7(3) = 21 9(3) = 27 When two ratios are equal Use cross products to solve proportions 9 = a 2 14 15 = 3 m+1 m x/6 = y/7 What ratio completes the equivalent proportion? x/y = ? 6/x = ? (y + 7)/7 = ? Pg. 436 #9 32, 40 43