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Evaluate $$\alpha=\int_{\pi \over 6}^{\pi \over 3}\frac{\sin t+\cos t}{\sqrt{\sin 2t}}dt$$

My attempt:

First I tried to substitute ${π \over 2}-x$, but didn't work .

Then I made square in denominator

$$\alpha=\int_{\pi \over 6}^{\pi \over 3}\frac{\sin t+\cos t}{\sqrt{(\sin t+\cos t)^2-1}}dt$$

I could put $\sin t + \cos t =x$ but above is not differentiation of it.

J. W. Tanner
  • 60,406
Rishi
  • 998

1 Answers1

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As $\dfrac{d(\sin x+\cos x)}{dx}=\sin x-\cos x$

set $u=\sin x-\cos x$

$\implies u^2=1-\sin2x\iff\sin2x=1-u^2$