2.1.2 Proportional Reasoning Key Objectives • Solve proportions.
• Solve percent problems using various methods. • Scale geometric figures in the coordinate plane. • Apply proportional relationships to rates, similarity, and scale. Key Terms
• A ratio is a comparison of two quantities using division. • A proportion is an equation that shows two equivalent ratios. • In a proportion a / b = c / d , where b ≠ 0 and d ≠ 0, the cross products ad and bc are equal. Example 1 Solving Proportions To solve a proportion containing a variable, set the cross products equal and then apply inverse operations.
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