1 / 9

Warm Up Find the cross products, and then tell whether the ratios form a proportion.

138 = 144; no. Warm Up Find the cross products, and then tell whether the ratios form a proportion. 16 6. 40 15. ,. 1. 240 = 240; yes. 3 8. 18 46. ,. 2. 8 9. 24 27. ,. 3. 216 = 216; yes. 28 12. 42 18. ,. 4. 504 = 504; yes. M. P. 100 m. ?. ?. ?. ?. ?. ?.

edna
Download Presentation

Warm Up Find the cross products, and then tell whether the ratios form a proportion.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 138 = 144; no Warm Up Find the cross products, and then tell whether the ratios form a proportion. 16 6 40 15 , 1. 240 = 240; yes 3 8 18 46 , 2. 8 9 24 27 , 3. 216 = 216; yes 28 12 42 18 , 4. 504 = 504; yes

  2. M P 100 m ? ? ? ? ? ? OP ST MN QR NO RS MP QT 60 m = = = 50 m = = = O 80 m N 80 320 60 240 50 200 100 400 Q T 400 m 1 4 1 4 1 4 1 4 = = = 240 m 200 m S R 320 m In similar figures the ratios of the lengths of the corresponding sides are proportional. Indirect measurementis a method of using proportions to find an unknown length or distance in similar figures. Write ratios using corresponding sides. Substitute the length of the sides.

  3. Finding Unknown Lengths in Similar Figures Find the unknown length in the similar figures. AC QS AB QR = Write a proportion using corresponding sides. 14 w 12 48 = Substitute lengths of the sides. 12 · w = 48 · 14 Find the cross product. 12w = 672 Multiply. 672 12 12w 12 = Divide each side by 12. w = 56 QR is 56 centimeters.

  4. x 10 cm Q R B A 24 cm 12 cm D C T Example 1 Find the unknown length in the similar figures. S AC QS AB QR = Write a proportion using corresponding sides. 10 x 12 24 Substitute lengths of the sides. = Find the cross product. 12 · x = 24 · 10 12x = 240 Multiply. 240 12 12x 12 Divide each side by 12. = x = 20 QR is 20 centimeters.

  5. Example 2: 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 product. Multiply. 8x = 24 8x 8 24 8 = Divide each side by 8. x = 3 The base of the inside triangle is 3 inches.

  6. Example 3 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 product. Multiply. 6w = 36 36 6 6w 6 = Divide each side by 6. w = 6 The right rectangle is 6 cm wide.

  7. 50 h 25 15 = 53 50 h = Example 4: Indirect Measurement City officials want to know the height of a traffic light. Find the height of the traffic light. Write a proportion. Simplify. 5h =150 Cross multiply. 25 ft h = 30 Divide each side by 5. 50 ft The traffic light is 30 feet high.

  8. h 30 5 15 = Example 5 The inside triangle is similar in shape to the outside triangle. Find the height of the outside triangle. Write a proportion. 13 h 30 h ft = Simplify. 5 ft Cross multiply. 1 • 30=3• h 15 ft Multiply. 30=3h 30 ft Divide each side by 3. 10=h The outside triangle is 10 feet tall.

  9. You Try Find the unknown length in each pair of similar figures. 1. 2. x = 120 cm t = 150 cm 3.The rectangles below are similar. The width of the smaller rectangle is 6in. The width of a larger rectangle is 9in. Estimate the length of the larger rectangle. 15 inches 6 in 9 in

More Related