This function has the correct amplitude and period. However, when $\displaystyle{x}=\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$ , the value of $\displaystyle{y}=-{5}{\cos{\pi}}=-{5}{\left(-{1}\right)}={5}\usepackage{cmbright}\Huge\$ . So it does not pass through $\displaystyle{\left(\frac{{1}}{{2}},-{5}\right)}\usepackage{cmbright}\Huge\$ .