$At$ each $of$ the points $(7,7,\frac{}{2}),(\frac{}{2},\frac{}{2},),(-9,9,\frac{5}{6}),$ evaluate the function $w(r,s,t)=\frac{r-s}{sin(t)}or$ indicate that the function $is$

undefined there.

$(Use$ symbolic notation and fractions where needed. $If$ the function $is$ undefined $at$ the given point, type UNDEFINED.$)$

$w(7,7,\frac{}{2})=$

$w(\frac{}{2},\frac{}{2},)=$

$w(-9,9,\frac{5}{6})$