7-5 Vocabulary Indirect measurement Scale drawing scale

7-5 Using Proportional Relationships Geometry

Indirect Measurement Any method that uses formulas, similar figures, &/or proportions to measure an object.

Ex. 1 Tyler wants to find the height of a telephone pole. He measured the pole’s shadow & his own shadow & then made a diagram. What is the height or h of the pole? h 5 ft 9 in 7 ft 8 in 38 ft 4 in

Scale drawing - represents an object as smaller than or larger than its actual size. The drawing’s scale is the ratio of any length in the drawing to the corresponding actual length.

Ex. 2 On a Wisconsin road map, Kristin measured a distance of 11 1/8 in. from Madison to Wausau. The scale of the map is 1 inch:13 miles. What is the actual distance from Madison & Wausau to the nearest mile?

Ex. 3 Lady Liberty holds a tablet in her left hand. The tablet is 7.19 m long & 4.14 m wide. If you made a scale drawing using the scale 1 cm:0.75 m, what would be the dimensions to the nearest tenth?

7.5 B Similarity Ratios & Theorem A D 5 4 10 8 B C 3 E 6 F Perimeter Ratio Area Ratio

7-5-1 7-5-1 Proportional Perimeters & Areas Thm If the similarity ratio of two similar figures is , then the ratio of their perimeters is , & the ratio of their areas is

Ex 1. Given that find the perimeter P & Area A of M R 13 cm 9.1 cm Q S P = 36 cm A = 60 cm² L N

Ex. 2 BC = 4mm, & EF = 12 mm. If P=42 mm & A = 96 mm² for Find the perimeter & area of