Correct option is (1) 240 m
H = \(\frac{(u sin\theta)^2}{2g}\)
80 = \(\frac{u^2sin^2\theta}{2g}\)
\(\frac{80\times2\times10}{2540}=sin^2\theta\)
16/25 = sin2θ
4/5 = sin θ
R = \(\frac{u^2sin2\theta}g\)
R = \(\frac{2500\times2sin\theta cos\theta}g\)
R = \(\cfrac{2500\times2\times\frac45\times35}{10}\)
R = 240 m