[tex]\large f(x)=e^{\tan^2x}
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\\ \large f'(x)=(e^{\tan^2x})'=e^{\tan^2x}(\tan^2{x})'=e^{\tan^2x}\times2\tan{x}(\tan{x})'=
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\\=2e^{\tan^2x}\tan{x}( \frac{\sin{x}}{\cos{x}} )'=2e^{\tan^2x}\tan{x} \frac{1}{\cos^2{x}} =2e^{\tan^2x} \times\frac{\sin{x}}{\cos{x}} \frac{1}{\cos^2{x}} =
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\\=2e^{\tan^2x} \times\frac{\sin{x}}{\cos^3{x}} }[/tex]