Finding Unknown Lengths in Similar Figures Course 2 Using Similar Figures Finding Unknown Lengths in Similar Figures AC QS = AB QR Write a proportion using corresponding sides. 12 48 14 w = Substitute lengths of the sides. 12 · w = 48 · 14 Find the cross product. 12w = 672 Multiply. 12w 12 672 12 = Divide each side by 12 to isolate the variable. w = 56 QR is 56 centimeters.

Insert Lesson Title Here Course 2 Using Similar Figures Insert Lesson Title Here Find the unknown length x 10 cm Q R A B 12 cm 24 cm D C S T AC QS AB QR = Write a proportion using corresponding sides. 12 24 10 x = Substitute lengths of the sides. 12 · x = 24 · 10 Find the cross product. 12x = 240 Multiply. 12x 12 240 12 = Divide each side by 12 to isolate the variable. x = 20 QR is 20 centimeters.

Measurement Application Course 2 Using Similar Figures Measurement Application A volleyball court is a rectangle that is similar in shape to an Olympic-sized swimming pool. Find the length of the pool. Let l = the length of the pool. 9 25 18 l Write a proportion using corresponding side widths. = 9 ·l = 18 · 25 Find the cross products. 9l = 450 Multiply. 9l 9 = 450 9 Divide each side by 9 to isolate the variable. l = 50 The pool is 50 meters long.

Insert Lesson Title Here Course 2 Using Similar Figures Insert Lesson Title Here The rectangle on the left is similar in shape to the rectangle on the right. Find the width of the right rectangle. 12 cm 6 cm 3 cm ? Let w = the width of the right rectangle. 6 12 3 w Write a proportion using corresponding side lengths. = 6 ·w = 12 · 3 Find the cross products. 6w = 36 Multiply. 6w 6 = 36 6 Divide each side by 6 to isolate the variable. w = 6 The right rectangle is 6 cm wide.

Using Indirect Measurement Course 2 Using Similar Figures Using Indirect Measurement City officials want to know the height of a traffic signal. The traffic light casts a shadow that is 45 ft long. A stop sign casts a shadow that is 30 ft long. If the stop sign is 15 ft high, what is the height of the traffic light? Let x = the height of the traffic light. 30 45 15 x = Write a proportion. 30 · x = 45 · 15 Find the cross product. 30 x = 675 Multiply. 30x 30 675 30 Divide each side by 30 to isolate the variable. = x = 22.5 The traffic light is 22.5 feet tall.

Insert Lesson Title Here Course 2 Using Similar Figures Insert Lesson Title Here The inside triangle is similar in shape to the outside triangle. Find the length of the base of the inside triangle. Let x = the base of the inside triangle. 8 2 12 x Write a proportion using corresponding side lengths. = 8 · x = 2 · 12 Find the cross products. 8x = 24 Multiply. 8x 8 24 8 = Divide each side by 8 to isolate the variable. x = 3 The base of the inside triangle is 3 inches.

Insert Lesson Title Here Course 2 Using Similar Figures Insert Lesson Title Here Lesson Quiz Find the unknown length in each pair of similar figures. J A 3. These two rectangular cakes are similar in shape. How long is the larger cake? 144 cm 1. 96 cm x 80 cm C K 56 cm B L 84 cm 10 in. x = 120 cm 6 in. x 2. 9 in. 160 cm 120 cm t 72 cm 90 cm x = 15 inches t = 150 cm