Concept:
At highest point, vertical velocity = 0.
Step 1: At \(t=3s\), motion is horizontal
\[
u\sin\theta = g \cdot 3
\]
Step 2: At \(t=2s\), direction \(30^\circ\)
\[
\tan 30^\circ = \frac{u\sin\theta - 2g}{u\cos\theta}
\]
Step 3: Solve
\[
u\sin\theta = 3g,\quad u\cos\theta = \sqrt{3}g
\]
\[
u = \sqrt{(3g)^2 + (g\sqrt{3})^2} = 20\sqrt{3}
\]
\[
\theta = 60^\circ
\]