Answer
$\dfrac{\sqrt3}{2}$
Work Step by Step
RECALL:
$(f \circ h)(x)=f\left(h(x)\right)$
Use the rule above to obtain:
$(g\circ p)(60^\circ)=g\left(p(60^\circ)\right)=g\left(\dfrac{60^\circ}{2}\right)=g(30^\circ)=\cos{30^\circ}=\dfrac{\sqrt3}{2}$
