E = 1 – sin^2x + cot^2x . sin^2x F = cos^4x + sin^2x . cos^2x + sin^2x

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1. $E=1-\sin^2x+\dfrac{\cos^2x}{\sin^2x}.\sin^2x$

   $=1-\sin^2x+\cos^2x$

   $=\cos^2x+\cos^2x$

   $=2\cos^2x$

   $F=\cos^4x+\sin^2x.\cos^2x+\sin^2x$

   $=\cos^2x.\cos^2x+\sin^2x.\cos^2x+\sin^2x$

   $=\cos^2x(\sin^2x+\cos^2x)+\sin^2x$

   $=\cos^2x+\sin^2x$

   $=1$

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2. Đáp án:$E=2Cos^2x\\F=1$

    

   Giải thích các bước giải:

    $E=1-sin^2x+cot^2x.sin^2x\\E=cos^2x+\dfrac{cos^2x}{sin^2x}.sin^2x\\E=2cos^2x\\F=cos^4x+sin^2x.cos^2x+sin^2x\\F=Cos^2x(Sin^2x+Cos^2x)+sin^2x\\=Cos^2x+Sin^2x\\=1$

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