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CalculusChallengeNon-Elementary Integration

Non-Elementary Integration · Challenge problem

Let A=∫0π/2sin⁡x dxA=\displaystyle\int_0^{\pi/2}\sqrt{\sin x}\,dx and B=∫0π/2dxsin⁡xB=\displaystyle\int_0^{\pi/2}\dfrac{dx}{\sqrt{\sin x}}; neither has an elementary value. Using ∫0π/2sin⁡2p−1xcos⁡2q−1x dx=Γ(p)Γ(q)2 Γ(p+q)\displaystyle\int_0^{\pi/2}\sin^{2p-1}x\cos^{2q-1}x\,dx=\dfrac{\Gamma(p)\Gamma(q)}{2\,\Gamma(p+q)}, Γ ⁣(12)=π\Gamma\!\left(\tfrac12\right)=\sqrt\pi and Γ(s+1)=s Γ(s)\Gamma(s+1)=s\,\Gamma(s), find ABAB.