Answer
$1$
Work Step by Step
RECALL:
$(f \circ h)(x)=f\left(h(x)\right)$
Use the rule above to obtain:
$\left(h\circ f\right)\left(\dfrac{5\pi}{6}\right)=h\left(f\left(\dfrac{5\pi}{6}\right)\right)=h\left(\sin{\left(\dfrac{5\pi}{6}\right)}\right)=h\left(\dfrac{1}{2}\right)=2\left(\dfrac{1}{2}\right)=1$
