Bell Work Write a congruence statement. ∆MNL ≅ ∆SRT

Two objects are similar if they are the same shape but different sizes. Similar Polygons

Example: Is the pair of polygons similar? Explain your answer. 5 m 8 m 10 m 13 m OR 5(13) = 10(8) 65 = 80 NO 5(13) = 8(10) 65 = 80 NO

Example: Is the pair of polygons similar? Explain your answer. 4 yd3 yd 6 yd 4.5 yd OR 4(4.5) = 6(3) 18 = 18 YES 4(4.5) = 6(3) 18 = 18 YES

15 ft9 ft 21 ft 12 ft Yes No Are the polygons similar? You must be able to justify your answer. (Shapes not drawn to scale.)

10 m 8 m 2.5 m 2 m Yes No Are the polygons similar? You must be able to justify your answer. (Shapes not drawn to scale.)

15 yd 6 yd 15 yd 37.5 yd Yes No Are the polygons similar? You must be able to justify your answer. (Shapes not drawn to scale.)

Example: Find the value of x in the pair of similar polygons. 15 cm x 6 cm 8 cm 10 cm OR 15(10) = 6x 150 = 6x 25 cm = x 15(10) = 6x 150 = 6x 25 cm = x

You try: Find the value of y in the pair of similar polygons. y 15 in 5 in 7.5 in 15(5) = 7.5x 75 = 7.5x 10 in = x 15(5) = 7.5x 75 = 7.5x 10 in = x Or

25 ft 18 ft 17.5 ft w Find the measure of the missing value in the pair of similar polygons. (Shapes not drawn to scale.) 12.6 ft A B C D 18ft 450ft.07 ft

17 m 4.25 m 4 mx Find the measure of the missing value in the pair of similar polygons. (Shapes not drawn to scale.) 16m 68ft A B C D 16.25m 18.06ft

11 mm38.5 mm 6 mm y Find the measure of the missing value in the pair of similar polygons. (Shapes not drawn to scale.) 21 mm 33.5mm A B C D 66mm 70.58mm

Scale Factor When you compare corresponding measurements of proportional objects, you get a ratio. This ratio is called the scale factor. What is the scale factor from the larger shape to the smaller one?

Practice: Similar Polygons Worksheet