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Substitute [tex]\displaystyle \begin{align*} u = \cos{ \left( \pi \, x \right) } \implies du = -\pi\sin{ \left( \pi \, x \right) } \, dx \end{align*}[/tex] to start with...how do i integrate sin(pi*x)*sqrt(1 + pi*2*cos(pi*x)^2)?
i reduced this to sqrt(u^2-u) but i don't know how to go from here