Math Problem Statement
- Find the volume of the solid obtained by rotating the region bounded by y = 3 \cos(x^2),y=0 ,x= 0 , x = \sqrt{\displaystyle\frac{\pi}{3}} and about the -axis.
Solution
To find the volume of the solid obtained by rotating the region bounded by the curves , , , and about the -axis, we can use the method of disks.
Step 1: Set up the volume integral
When rotating a region about the -axis, the volume is given by:
Here:
- The bounds are to .
So the volume integral becomes:
Step 2: Simplify the integrand
Simplify the integrand:
Factor out the constant:
Step 3: Use an appropriate substitution or numerical methods
The integral does not have an elementary antiderivative. Therefore, this integral is typically evaluated using numerical methods.
However, we can express the integral using the half-angle identity for cosine:
For our integral:
Thus, the integral becomes:
Simplifying:
This integral can be split into two parts:
The first integral is straightforward:
The second integral does not have a simple closed form and is usually evaluated numerically.
Let's denote this integral by :
Thus, the volume becomes:
Step 4: Compute the numerical value
The integral can be computed numerically, but we can provide a simplified expression here:
Since is a definite integral, it is a fixed number that can be approximated using numerical integration methods such as Simpson's rule, trapezoidal rule, or using a calculator or software.
Final Answer:
The volume of the solid obtained by rotating the region bounded by , , , and about the -axis is given by:
where is the integral , which needs to be evaluated numerically for an exact value.
If you need the exact numerical value, I can help compute it. Let me know!
Here are 5 related questions:
- How do you approach integrals that do not have elementary antiderivatives?
- What is the half-angle identity, and how is it used in integration?
- How can you evaluate integrals numerically?
- What are some alternative methods for finding volumes of revolution?
- How does the choice of axis of rotation affect the integral setup?
Tip: When dealing with complex integrals that do not have elementary solutions, consider using numerical methods or computer algebra systems to approximate the result.
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Math Problem Analysis
Mathematical Concepts
Volume of Revolution
Integration
Trigonometric Substitution
Formulas
Volume integral using disks/washers
Theorems
-
Suitable Grade Level
University Level
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