Question 4 - A-Level Maths

Show that the equation $\frac { 4 \cos \theta } { \tan \theta } + 15 = 0$ can be expressed as $$4 \sin ^ { 2 } \theta - 15 \sin \theta - 4 = 0$$
Hence solve the equation $\frac { 4 \cos \theta } { \tan \theta } + 15 = 0$ for $0 ^ { \circ } \leqslant \theta \leqslant 360 ^ { \circ }$.