Skills and Concepts
- To write ratios
- To find equal ratios
A ratio is a comparison of two quantities by division. You can write the same ratio in three ways. To find equal ratios, multiply or divide the numerator and denominator by the same nonzero number.
5-2 and 5-3 Objectives
- To find unit rates
- To use unit prices
- To solve a problem using two different methods
A rate is a ratio that compares two quantities measured in different units. A unit rate has a denominator of 1. Find a unit price by dividing the price of an item by the size of the item.
You can use different strategies to solve the same problem.
5-4 and 5-5 Objectives
- To test if ratios can form a proportion
- To use cross products
- To use unit rates to solve proportions
- To solve proportions involving variables
A proportion is an equation stating that two ratios are equal. If two ratios form a proportion, the cross products are equal.
- To identify similar figures
- To find missing lengths in similar figures
Two polygons are similar polygons if corresponding angles have equal measure and the lengths of corresponding sides form equal ratios.
- To use proportions to solve problems involving scale
A scale drawing is an enlarged or reduced drawing of an object that is similar to the actual object. A scale is a ratio that compares a length in a drawing to the corresponding length in the actual object.