Chapter 8 Lesson 1 Objective: To write ratios and solve proportions.

A proportion is a statement that two ratios are equal. You can write a proportion in these forms: proportion and a : b = c : d and a : b = c : d When three or more ratios are equal, you can write an extended proportion. For example, you could write the following: extended proportion. extended proportion.

Properties of Proportions Properties of Proportions Cross-Product Property: The product of the extremes of a proportion is equal to the product of the means.

Example 1: Properties of Proportions If, complete each statement. Flip the Fractions. Top + Bottom ÷ by bottom Think:

Example 2: Solving for a Variable Solve each proportion. a.) Cross Multiply b) Distributive Prop.

Example 3: Solving for a Variable Solve each proportion. a.) Cross Multiply b.)

In a scale drawing, the scale compares each length in the drawing to the actual length. The lengths used in a scale can be in different units. A scale might be written as 1 in. to 100 mi, 1 in. = 12 ft, or 1 mm : 1m. You can use proportions to find the actual dimensions represented in a scale drawing. scale drawing,scale drawing,scale

Example 4: Solving for a Variable Measure the dimensions of the bedroom in the scale drawing. Use those dimensions to find the dimensions of the actual bedroom. Use a ruler to find that the bedroom in the scale drawing is in. by in. The actual bedroom is 14 ft by 10 ft.

Assignment Pages 418 – 420 Pages 418 – 420 #1-28; #1-28; 30-42