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## Homework Statement

[tex]\int \frac{cosx dx}{\sqrt{1 + sin^{2}x}}[/tex]

## Homework Equations

Expression: [tex]\sqrt{a^{2} + x^{2}}[/tex]

Substitution: x = a*tan[tex]\Theta[/tex]

Identity: 1 + tan[tex]^{2}\Theta = sec^{2}\Theta[/tex]

## The Attempt at a Solution

I have tried using Trig Substitution, but I end up getting an equation much like the one I started only it contains secants and tangents instead of cosine and sine. For some reason I only see a circular route that would just take me back to the original equation.

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