SS 3.4 Additional Practice w/ Similar Figures 1) Teaching Target: I can use equivalent ratios to compare corresponding sides of similar rectangles. 2) Homework: Complete notes for Inv 4.2 on p. 12 – for the Zaption video 4.2 Warm-Up: 10 cm 8 cm What is the ratio of height to width? Ratios describe and compare shapes.

Vocab Toolkit: Ratios whose fraction representations are equivalent are called equivalent ratios. A comparison of two quantities: the ratio of 3 to 5 means ‘3 for every 5.’ An equation stating that two ratios are equal. 3/5 3 to 5 3 : 5

Original to 8 8 to 3 3 to 6 5 to 4

HW Review p. 12: ratios comparison 10 cm 8 cm fraction equivalent fractions width height width or

scale factor proportionequal height width X 1.5 X = 12 width height OR 8 10 X 15 =

Which figures are similar? For each rectangle, find the ratio of the length of the short side to the length of the long side. 20 in. 15 in. 10 in. 12 in. 9 in. 6 in. A B C D pkt p. 11

12 : 20 6 : 10 9 : 15 6 : = = = = B, C A, C A, B not similar Similar rectangles have the SAME ratio! Non-similar rectangles have different ratios!

12 : 20 6 : 10 9 : 15 6 : = = = = B, C A, C A, B not similar B to A =B to C =C to A = B A C D How many times greater or smaller each side length and perimeter will be. 4. Choose two similar rectangles. Find the scale factor from the smaller to the larger. What does the scale factor tell you? 21.54/3

12 : 20 6 : 10 9 : 15 6 : = = = = B, C A, C A, B not similar B A C D B to A =B to C =C to A = 21.54/3 5. Compare the information given by the scale factor to the information given by the ratios of side lengths.

Homework: Complete notes for Inv 4.2 on p. 12 – for the Zaption video 4.2 Did I Hit My Learning Target? I can use equivalent ratios to compare corresponding sides of similar rectangles.

F and G are similar. They have the same angle measure for corresponding angles. AND, each of the corresponding sides has the same scale factor. For each parallelogram, find the ratio of the length of a long side to the length of a short side. How do the ratios compare? They all have equal ratios: EXTRA PRACTICE:

Scale Factor: B to A = 2 B to C = 1.5 C to A = Ratio of short side to long side Similar figures have a constant scale factor and their ratios of corresponding side lengths will be equivalent. The scale factor gives the amount of stretching (or shrinking) from the original figure to the image. The ratio of adjacent side lengths within a figure gives an indication of the shape of the original figure (and image), since it compares measures within one figure.

A, B, and C are similar! 6 x 1.5 =9 10 x 1.5 = 15 SF for B to C is x.75 =15 12 x.75 = 9 SF for A to C is.75 6 x 2 =12 10 x 2 = 20 SF for B to A is 2 6 x 1 =6 10 x 2 = 20 SF for B to D is NOT CONSISTENT IF “D” IS NOT SIMILAR TO “B”, IT ISN’T SIMILAR TO “A” OR “C”