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