The minimum value of the function is $\displaystyle-{1}\usepackage{cmbright}\Huge\$ . To put this another way, the least output of the function, or value of $\displaystyle{\sin{\theta}}\usepackage{cmbright}\Huge\$ , is $\displaystyle-{1}\usepackage{cmbright}\Huge\$ . The question was asking for the inputs, or values of $\displaystyle\theta\usepackage{cmbright}\Huge\$ , that yield this output.