Solution
= Solution
A <probability density function> must have total <integral> one. Put $h=\pi/6$. The term $ax$ is an <odd function>, so
$$
1=\int_{-h}^{h}(ax+b\cos x)\,dx=2b\sin h=b.
$$
Thus $\boxed{b=1}$.
= Solution
A <probability density function> must have total <integral> one. Put $h=\pi/6$. The term $ax$ is an <odd function>, so
$$
1=\int_{-h}^{h}(ax+b\cos x)\,dx=2b\sin h=b.
$$
Thus $\boxed{b=1}$.