[tex]\bf sin^2(\theta)+cos^2(\theta)=1\implies sin^2(\theta)=1-cos^2(\theta)\\\\
-------------------------------\\\\
\underline{sin^2(\theta )}+cos(\theta )=2\implies \underline{1-cos^2(\theta )}+cos(\theta )=2
\\\\\\
0=cos^2(\theta )-cos(\theta )+1[/tex]
