# Approximating Area

How a quantity changes is a very important concept in business and economics. In earlier chapters, we examined several functions like the revenue, cost and profit functions. From these functions, we are able to calculate the rate at which each function changes. The mathematical concept of a derivative helped us to understand how quantitative decisions may be made about these functions.

In this section, we reverse this process. Starting from the rate of change of some function, we’ll calculate information about the function itself. For instance, by knowing the rate of change of revenue, we can calculate how revenue changes when production is changed. In this context, area becomes very important. We’ll examine how area relates to this process and extend the concept to calculate the area under a function.

**Read **in Section 13.2

- Why is area important?
- How is the area under a function approximated?
- Handout: Area with Rectangles
- Handout: Left and Right Hand Sums from Table

Section 13.2 Workbook (PDF)– 9/5/19

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