Integral of (sin (x))^1/2)(cos^3(x)) dx

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The discussion focuses on solving the integral of (sin(x))^1/2 * (cos^3(x)) dx. Participants suggest converting the integral to include only sine terms by applying the trigonometric identity cos^2(x) = 1 - sin^2(x). This transformation simplifies the integral, making it easier to solve. Additionally, a request for help with the integral of (sin(ln x))/x dx is made, with a recommendation to use the substitution u = ln x. The conversation emphasizes the importance of transforming integrals to facilitate easier computation.
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Not really sure where to begin on this integral. Hope this reads alright on here.

Integral of (sin (x))^1/2)(cos^3(x)) dx
 
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\int {\sqrt{sin(x)}} cos(x)^3 dx

Convert this into

\int {\sqrt{sin(x)}}cos^2(x)cos(x).

From your identities in trignometry

cos^2(x) = 1 - sin^2(x).

This will leave you with all sine terms and one cosine term once you rewrite cosine squared. Do you see what to do from here?
 
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That was very helpful, thank you. Could I also get help with this one pls? :) I just seem to have a hard time figuring out where to start on these.

The integral of (sin(ln x))/x dx
 
Jeann25 said:
That was very helpful, thank you. Could I also get help with this one pls? :) I just seem to have a hard time figuring out where to start on these.

The integral of (sin(ln x))/x dx

Use a substitution letting u = ln x.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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