Question

sin^{2} theta +cos theta = 2
Use the pythagorem identity sin^{2} theta +cos^{2} theta =1 to replace sin^{2} theta in the given equation

Answer 1

$\bf sin^2(\theta)+cos^2(\theta)=1\implies sin^2(\theta)=1-cos^2(\theta)\\\\ -------------------------------\\\\ \underline{sin^2(\theta )}+cos(\theta )=2\implies \underline{1-cos^2(\theta )}+cos(\theta )=2 \\\\\\ 0=cos^2(\theta )-cos(\theta )+1$