lowest points: $\displaystyle{\left(-\frac{\pi}{{2}},-{1}\right)}\usepackage{cmbright}\Huge\$ and $\displaystyle{\left(\frac{{{3}\pi}}{{2}},-{1}\right)}\usepackage{cmbright}\Huge\$ ; highest point: $\displaystyle{\left(\frac{\pi}{{2}},{1}\right)}\usepackage{cmbright}\Huge\$