Question 9 - A-Level Maths

It is given that $\sec x - \tan x = - 5$.
1. Show that $\sec x + \tan x = - 0.2$.
2. Hence find the exact value of $\cos x$.
Hence solve the equation $$\sec \left( 2 x - 70 ^ { \circ } \right) - \tan \left( 2 x - 70 ^ { \circ } \right) = - 5$$ giving all values of $x$, to one decimal place, in the interval $- 90 ^ { \circ } \leqslant x \leqslant 90 ^ { \circ }$.
[0pt] [3 marks] \section*{DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED}