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lim-x-pi-2-sin-x-tanx-




Question Number 71894 by 20190927 last updated on 21/Oct/19
lim_(x→(π/2)) (sin x)^(tanx)
$$\underset{{x}\rightarrow\frac{\pi}{\mathrm{2}}} {\mathrm{lim}}\left(\mathrm{sin}\:\mathrm{x}\right)^{\mathrm{tanx}} \\ $$
Commented by kaivan.ahmadi last updated on 21/Oct/19
=e^(lim_(x→(π/2)) (sinx−1)tanx) =e^(lim_(x→(π/2)) ((sinx−1)/(cotx))) =    e^(lim_(x→(π/2)) ((cosx)/(−(1+cot^2 x)))) =e^0 =1
$$={e}^{{lim}_{{x}\rightarrow\frac{\pi}{\mathrm{2}}} \left({sinx}−\mathrm{1}\right){tanx}} ={e}^{{lim}_{{x}\rightarrow\frac{\pi}{\mathrm{2}}} \frac{{sinx}−\mathrm{1}}{{cotx}}} =\:\: \\ $$$${e}^{{lim}_{{x}\rightarrow\frac{\pi}{\mathrm{2}}} \frac{{cosx}}{−\left(\mathrm{1}+{cot}^{\mathrm{2}} {x}\right)}} ={e}^{\mathrm{0}} =\mathrm{1} \\ $$

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