6.2 Trigonometric Functions: Unit Circle Approach/109

$f(x)=\sin(x)$
$g(x)=\cos(x)$
$h(x)=2x$
$p(x)={\frac {x}{2}}$

$(f\cdot g)(30^{\circ })=h(p(30^{\circ })=h\left({\frac {30^{\circ }}{2}}\right)=h(15^{\circ })=2\cdot 15^{\circ }=30^{\circ }$