Calc II: Help Solving this Integral

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SUMMARY

The integral discussed is ∫ (√(9 - x²)/x) dx, which is approached using the substitution x = 3sin(u). The differential dx is expressed as 3cos(u)du, leading to the integral transformation into ∫ (cos(u)/sin(u)) cos(u) du. The solution involves rewriting cos²(u) as 1 - sin²(u) and splitting the integral into two parts for easier evaluation. This method effectively simplifies the integration process.

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Homework Statement



[itex]\int \frac{\sqrt{9 - x^2}}{x} dx[/itex]

2. The attempt at a solution

x = 3sin(u)
dx = 3cos(u)du
u = arcsin(x/3)

[itex]\int \frac{3\sqrt{cos(u)^2}}{3sin(u)} 3cos(u)du[/itex]

[itex]3 \int \frac{cos(u)}{sin(u)} cos(u)du[/itex]

Don't really see anywhere to go from here. Apologies if the work is hard to follow, I cut out a few steps because inputting equations is a real pain in my opinion.
 
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Hertz said:

Homework Statement



[itex]\int \frac{\sqrt{9 - x^2}}{x} dx[/itex]

2. The attempt at a solution

x = 3sin(u)
dx = 3cos(u)du
u = arcsin(x/3)

[itex]\int \frac{3\sqrt{cos(u)^2}}{3sin(u)} 3cos(u)du[/itex]

[itex]3 \int \frac{cos(u)}{sin(u)} cos(u)du[/itex]

Don't really see anywhere to go from here. Apologies if the work is hard to follow, I cut out a few steps because inputting equations is a real pain in my opinion.

Write cos2(u) as 1 - sin2(u), and then split into two integrals.
 
Mark44 said:
Write cos2(u) as 1 - sin2(u), and then split into two integrals.

Ah! Thank you, I'll give it a try
 

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