These two triangles are called Similar Figures 1

These two triangles are called Similar Figures. 1. Why do you think that is true? 2. What do you think the words Similar Figures mean? a c f d b e If side a was 5 cm, side b was 3 cm, side c was 8 cm, and side d was 10 cm, 3. Could you tell me the length of side e? 4. Could you tell me the length of side f? 5 cm a c 8 cm b 3 cm f 10 cmd e You can find the answers because these Similar Figures are also in Proportion to each other, so you can use proportions to find your answers. Lets try it!

In your ISN. . . • If the two triangles are similar, which side is congruent to • AB • BC • AC

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How to use Proportions to find missing sides or numbers. 5 cm 8 cm 3 cm Divide with remaining number Corresponding Sides 5 cm Multiply= across 10 cm 3 cm NN Corresponding Sides f 10 cm 6 cm N 3 cm • 10 cm ÷ 5 cm = N 30 cm ÷ 5 cm = 6 cm 5. What is the measure of the side f ? 6. Write out the proportion you used to find the missing measure for side f.

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Homework • Page 543 –#1 - 14

Scale Drawing is like Similar Figures except that you only see one of the similar figures. ( Ex. A State road map )-( The map gives you a scale measurement to help you determine the actual distance. 1 inch : 3 miles ) 2 inches Scale Model of the new 1 in : 3. 5 ft School Banner 7 inches Use the scale to find the actual size of the banner. …. (Hint- set up a proportion with similar labels instead of sides) 7 & 8. Set up and show the proportion and give the correct length in feet? 9 & 10. Set up and show the proportion and give the correct height in feet?

6 -3 Homework “Scale Drawing & Similar Figures” Name: _________ Hour: _____ Each pair of triangles is similar. Find the missing length. Round to the nearest tenth if necessary. 2 in. 1. 2. x 10 in. y 10 in. 3 cm 4 in. 3. 8 cm 7 cm z 5 cm 12 cm 4. 8 cm 30˚���� � 7 cm 6. 4 cm 30˚���� a�

The scale of a map is 2 cm : 15 km. Find the actual distance for each map distance. 5. 6 cm = _____km 6. 2. 1 cm = _____km 7. 10 mm = _____km 8. 17. 4 cm = _____km The scale drawing has a scale of 1/2 in. : 10 ft. Find the length on the drawing for each actual length. 9. 40 ft = ________in 10. 5 ft = _________in 11. 35 ft = ________in 12. 3 1/2 ft = ________in Solve Each Proportion. 13. x = 5 32 80 14. 3 = 8 r 15. 24 = 204 16 . c

Sample Problems The scale of a map is 2 cm : 15 km. Find the actual distance for each map distance. 1. 3 cm = _____km 3 cm = 2 cm ? km 15 km 22. 5 km 2. 10 mm = _____km 1 cm 10 mm = 2 cm ? km ? km 15 km 7. 5 km 3 • 15 ÷ 2 = 22. 5 1 • 15 ÷ 2 = 7. 5 The scale drawing has a scale of 1/2 in. : 10 ft. Find the length on the drawing for each actual length. 4 2 in = ? in 80 ft 3. 80 ft = ________in 2. 5 4. 70 ft = ________in Solve Each Proportion. 5. x = 5 15 25 5 • 15 ÷ 25 = x 0. 5 in 10 ft 2. 5 in ? in = 0. 5 in 70 ft 10 ft 0. 5 • 80 ÷ 10 = 4 0. 5 • 70 ÷ 10 = 2. 5 **(Simplyify fraction and then solve. ) 6. 3 = 4 3 • 7 ÷ 4 = r r 7 7. 24 = 204 16 . c 204 • 16 ÷ 24 = x