# How could an architect change the size of How could an architect change the size of a blueprint? 12 ft 16 ft (1 inch grid) In this lesson you will learn how to make a new scale drawing from a given one by using ratios and proportions. Lets

Review Lets Review A proportion is an equation that relates two equal ratios. For example: = Lets Review Lets Review Solve a proportion by cross multiplying = Extreme s

Means (5)(n) = (8)(25) 5n = 200 n = 40 A Common Lets Review Mistake Mixing up the order of one ratio in a proportion 8 16 22

M 11 12 A 24 = L C N -

B CoreReview Lesson Lets Measurements from a scale drawing d Drawing: de = 4 in 6 in 4 in e 7 in

(1 in = 3 feet) = f 1(de) = 3(4) Actual: de = 12 ft CoreReview Lesson Lets 4 in (12 ft) e d

Make a new scale drawing 6 in 7 in NEW : old = 30 : 12 = 5 : 2 f = D 10 (30inft) E

15 in 5(4) = 2(DE) 17.5 in (1 in = 3 F DE = 10 in CoreReview Lesson Lets Original drawing:

12 ft (6 in) 16 ft (8 in) (1 inch grid) LONG SIDE: 20 feet LARGE : small = 20 : 16 = 5 : 4 = = 5(8) = 4(LONG) 5(6) = 4(SHORT) 40 = 4(LONG)

30 = 4(SHORT) LONG = 10 in SHORT = 7.5 in In this lesson you have learned how to make a new scale drawing from a given one by using ratios and proportions. Guided Practice Lets Review Find the side length, in cm, of each scale

drawing if the scale factor is 4/5. 28 meters (1 cm = 2 meters) Extension Lets ReviewActivities Using the given scale, which of the following measurements on the drawing below is incorrect? Explain. Scale: 1 in = 2 mi 6 in (12 mi) 20 in (10 mi) Extension Lets

ReviewActivities Using the given scale, find the length, in cm, of each side of the scale drawing for a trapezoid that is similar to this one, but twice as large. 11 m 9m 9m (2 cm = 3 meters) 16 m Quick Quiz Lets Review

1. Find the actual base and height of the region represented by the scale drawing. 14 cm 24 cm (1 cm = 3 m) Quick Quiz Lets Review 2. Two scale drawings are shown, and both use the same scale factor. How many inches will BC measure? B M

4 mi C N L 8 mi (1 in = 2 mi) A 12 mi