How can I solve this integral involving cosine and sine functions?

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In summary, the conversation discusses different approaches for integrating the function ∫cos^3(x)/√sin(x)dx. The person tried substituting sin(x) with t and using the formula dt=cos(x)dx, which led to an integral of ∫cos^2(x)/√t dt. They then transformed cos^2(x) into 1-sin^2(x) and got to ∫(1-t^2)/√t dt. They proposed splitting this into two smaller integrals but were unsure if it was the correct approach. The other person mentioned that both methods are correct, with Wolfram suggesting a different substitution. Ultimately, the conversation ends with the person thanking the other for their help
  • #1
lukatwo
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Homework Statement



I've been trying to integrate the following: ∫[STRIKE][itex]\frac{cos^3(x)}{\sqrt{sin(x)}}[/itex][/STRIKE]dx

Homework Equations


The Attempt at a Solution



First, I substituted sin(x) with t, and got dt=cos(x)dx => dx=[itex]\frac{dt}{cos(x)}[/itex].
After that I got ∫[STRIKE][itex]\frac{cos^2(x)}{\sqrt{t}}[/itex][/STRIKE]dt
Then i transformed cos^2(x) into 1-sin^2(x), and finally got to ∫[STRIKE][itex]\frac{1-t^2}{\sqrt{t}}[/itex][/STRIKE]dt

I thought I could just disintegrate them into two smaller integrals like ∫[STRIKE][itex]\frac{1}{\sqrt{t}}[/itex][/STRIKE]dt - ∫[STRIKE][itex]\frac{t^2}{\sqrt{t}}[/itex][/STRIKE]dt , and solve them easily, and then reverse the substitution.

Wolfram proposes that i cannot(?) do that, or rather prefers that I do another substitution.

I even tried to make it a defined integral, and calculate the values between the Wolfram solution, and my own. They differ by 0.1 or something similar.

Can someone explain what is the right way to do it?
 
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  • #2
Both are correct. Wolfram just does another substitution which isn't really too necessary. Both give the same correct integral.
 
  • #3
Thank you very much for your help!
 

Related to How can I solve this integral involving cosine and sine functions?

What is "integral solving problem"?

Integral solving problem is a mathematical concept that involves finding the area under a curve or the sum of infinitely small rectangles to solve a problem. It is commonly used in calculus and other areas of mathematics.

What is the purpose of solving integrals?

The purpose of solving integrals is to find the exact value of a quantity that cannot be easily measured or calculated. It can also be used to find the rate of change, total distance traveled, or total amount of something.

How do you solve an integral?

To solve an integral, you need to use integration techniques such as substitution, integration by parts, or partial fractions. You also need to have a good understanding of the fundamental theorem of calculus and the properties of integrals.

What is the difference between definite and indefinite integrals?

A definite integral has specific limits of integration and gives a numerical value for the integral. An indefinite integral has no limits of integration and gives a general solution in the form of a function.

What are some real-life applications of integrals?

Integrals have many applications in the real world, such as calculating the area under a graph to find the total distance traveled by a moving object, finding the volume of irregular shapes, and determining the average value of a function over a given interval. They are also used in physics, engineering, economics, and other fields to solve various problems.

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