Consider the two variable function $f(x,y)=sin(x)sin(y)$ on the domain $0x$ and $0y.$

$($a$)$ Graph the level curve $f(x,y)=0.$

$($b$)$ Graph the level curve $f(x,y)=1.$

$($c$)$ Graph the level curve $f(x,y)=\frac{1}{2}.$ Use implicit differentiation to find $\frac{dx}{dy}.$ Use your work to find all the horizontal and vertical tangent lines in the domain.