(i) Given that

\(3 \sin^2 x - 8 \cos x - 7 = 0\),

show that, for real values of \(x\),

\(\cos x = -\frac{2}{3}\).

(ii) Hence solve the equation

\(3 \sin^2(\theta + 70^\circ) - 8 \cos(\theta + 70^\circ) - 7 = 0\)

for \(0^\circ \leq \theta \leq 180^\circ\).