[tex]\bf \textit{Pythagorean Identities}
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1+tan^2(\theta)=sec^2(\theta)\\\\
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1+sec^2(x)sin^2(x)=sec^2(x)
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1+\cfrac{1}{cos^2(x)}\cdot sin^2(x)\implies 1+\cfrac{sin^2(x)}{cos^2(x)}\\\\\\ 1+tan^2(x)\implies sec^2(x)[/tex]