\(R=24\) also,\(\frac{H}{R}=\frac{1}{4} \tan \theta\)

\(\frac{H}{R}=\frac{1}{2} \Rightarrow \frac{1}{2}=\frac{1}{4} \tan \theta\)

\(\tan \theta=2=\frac{P}{B}\)

\(R=\frac{2 u^2 \sin \theta \cos \theta}{g}\)

\(R=\frac{2 u^2}{g} \cdot \frac{2}{\sqrt{5}} \times \frac{1}{\sqrt{5}}\)

\(R=\frac{4 u^2}{5 g}\)