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# 6: Using Definite Integrals

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• 6.1: Using Definite Integrals to Find Area and Length
A single definite integral may be used to represent the area between two curves. To find the area between two curves, we think about slicing the region into thin rectangles. The shape of the region usually dictates whether we should use vertical rectangles of thickness or horizontal rectangles of thickness.
• 6.2: Using Definite Integrals to Find Volume
Just as we can use definite integrals to add the areas of rectangular slices to find the exact area that lies between two curves, we can also employ integrals to determine the volume of certain regions that have cross-sections of a particular consistent shape. We can use a definite integral to find the volume of a three-dimensional solid of revolution that results from revolving a two-dimensional region about a particular axis by taking slices perpendicular to the axis of revolution which will t
• 6.3: Density, Mass, and Center of Mass
For an object of constant density D, with volume V and mass m, we know that m = D·V. If an object with constant cross-sectional area (such as a thin bar) has its density distributed along an axis according to the function ρ(x), then we can find the mass of the object between
• 6.4: Physics Applications - Work, Force, and Pressure
While there are many different formulas that we use in solving problems involving work, force, and pressure, it is important to understand that the fundamental ideas behind these problems are similar to several others that we’ve encountered in applications of the definite integral. In particular, the basic idea is to take a difficult problem and somehow slice it into more manageable pieces that we understand, and then use a definite integral to add up these simpler pieces.
• 6.5: Improper Integrals
An integral can be improper if at least one the limits of integration is ±∞, making the interval unbounded, or if the integrand has a vertical asymptote. When we encounter an improper integral, we work to understand it by replacing the improper integral with a limit of proper integrals.
• 6.E: Using Definite Integrals (Exercises)
These are homework exercises to accompany Chapter 6 of Boelkins et al. "Active Calculus" Textmap.

## Contributors

Matt Boelkins (Grand Valley State University), David Austin (Grand Valley State University), Steve Schlicker (Grand Valley State University)