The first point is on the graph of cosine, but the second point is on the graph of sine. When $\displaystyle\theta=\frac{\pi}{{2}}\usepackage{cmbright}\Huge\$ :

$\displaystyle{\cos{{\left(\frac{\pi}{{2}}\right)}}}={{\cos{{90}}}}^{\circ}={0}\usepackage{cmbright}\Huge\$

So the point $\displaystyle{\left(\frac{\pi}{{2}},{0}\right)}\usepackage{cmbright}\Huge\$ is on the graph of cosine.