Question

How do I solve this?

Answer 1

$\bf 4sin(\theta)+1=3\implies 4sin(\theta)=2\implies sin(\theta)=\cfrac{2}{4} \\\\\\ sin(\theta)=\cfrac{1}{2}\implies sin^{-1}[sin(\theta)]=sin^{-1}\left( \cfrac{1}{2} \right)\implies \theta=sin^{-1}\left( \cfrac{1}{2} \right)$