It appears that you found the value of $\displaystyle{\sin{{\left(\frac{{{7}\pi}}{{6}}\right)}}}\usepackage{cmbright}\Huge\$ . Convert $\displaystyle\frac{{{7}\pi}}{{4}}\usepackage{cmbright}\Huge\$ to degrees: this equals $\displaystyle{{315}}^{\circ}\usepackage{cmbright}\Huge\$ . Find the y-coordinate of the point where $\displaystyle{{315}}^{\circ}\usepackage{cmbright}\Huge\$ intersects the unit circle. The correct answer is: $\displaystyle-\frac{\sqrt{{2}}}{{2}}\usepackage{cmbright}\Huge\$