1.  Geometry 7.1 SWLT: Use Ratios and Proportions

2. Key Terms  Ratio:  A comparison of two nonzero numbers  Can be written three different ways  3 to 4, 3:4, or  Proportion:  A comparison of two equal ratios

3. Simplifying Ratios  Example 1:  20 cm : 60 cm  Write as a Fraction  Simplify  Can be read in fraction form or 1:3 or 1 to 3  Example 2  3 ft. : 18 in.   Make sure the quantities are measured in the same units!

4. Solving Proportions  5(9) = 3x  45 = 3x  x = 15  Cross Multiply  Solve for x (Divide)

5. Map Activity 2011 Green Bay Packers  Wild Card – Philadelphia  Divisional Round – Atlanta  Conference Championship – Chicago  Super Bowl – Arlington Texas 2013 Baltimore Ravens  Wild Card – Indianapolis  Divisional Round – Denver  Conference Championship – Boston  Super Bowl – New Orleans Using maps and string, set up proportions to find out which Super Bowl Winner traveled the most. The scale on the provided maps is 4.2 cm to 150 miles.

6. Using Ratios…Geometry  The perimeter of a rectangle is 80 feet. The ratio of the length to the width is 7:3. Find the the length and width of the rectangle  Use the perimeter formula  P = 2l + 2w  Substitute the given values for length, width and perimeter.  80 = 2(7x) + 2(3x)  80 = 14x + 6x  80 = 20x  x = 4  Length = 7(4) = 28  Width = 3(4) = 12 7x 3x

7. Using Proportions… Word Problems  Critics say that Ryan Howard is on track for his least productive full season since he hit 31 HR’s in 2010. He’s hit 5 HR to 70 At Bats.  If Ryan Howard bats 570 times, are his critics right?  Use the given ratio of HR : At Bats to set up a proportion  Solve the proportion  5(570) = 70HR  2850 = 70HR  HR ≈ 40.7  Ryan Howard is on pace to hit 41 Home Runs