Question 3 - A-Level Maths

3 The reflex angle \(\theta\) is such that \(\cos \theta = k\), where \(0 < k < 1\).

Find an expression, in terms of \(k\), for
(a) \(\sin \theta\),
(b) \(\tan \theta\).
Explain why \(\sin 2 \theta\) is negative for \(0 < k < 1\).