let's say that sin(θ) = x, then the cos(θ) which is twice the sine has to be 2x, therefore then
[tex]\bf tan(\theta )=\cfrac{sin(\theta )}{cos(\theta )}~~ \begin{cases} sin(\theta )=x\\ cos(\theta )=2x \end{cases}\implies tan(\theta )=\cfrac{x}{2x}\implies tan(\theta )=\cfrac{1}{2}[/tex]
