## Precalculus (10th Edition)

$\dfrac{\sqrt2}{4}$
RECALL: $(f \circ h)(x)=f\left(h(x)\right)$ Use the rule above to obtain: $(p\circ g)(315^\circ)=p\left(g(315^\circ)\right)=p(\cos{315^\circ})=p\left(\dfrac{\sqrt2}{2}\right)=\dfrac{\frac{\sqrt2}{2}}{2}=\dfrac{\sqrt2}{4}$