On the interval $\displaystyle-\pi\le\theta\le{0}\usepackage{cmbright}\Huge\$ , the graph is a ''valley.'' It starts at $\displaystyle{\left(-\pi,{0}\right)}\usepackage{cmbright}\Huge\$ , decreases down to the lowest point $\displaystyle{\left(-\frac{\pi}{{2}},-{1}\right)}\usepackage{cmbright}\Huge\$ , and then increases up to $\displaystyle{\left({0},{0}\right)}\usepackage{cmbright}\Huge\$ . The range is the set of outputs or y values of the function. These are between $\displaystyle-{1}\usepackage{cmbright}\Huge\$ and 0, so the range is $\displaystyle-{1}\le{y}\le{0}\usepackage{cmbright}\Huge\$ .