Question 3 - A-Level Maths

Express $2 \tan ^ { 2 } \theta - \frac { 1 } { \cos \theta }$ in terms of $\sec \theta$.
Hence solve, for $0 ^ { \circ } < \theta < 360 ^ { \circ }$, the equation $$2 \tan ^ { 2 } \theta - \frac { 1 } { \cos \theta } = 4$$