If for the same range, the two heights attained are 20 m and 80 m, then the range will be

According to given condition, h1h2=sin2θsin290°-θ=2080⇒  tan2θ=14⇒tanθ=12sinθ=15 and cosθ=25So,  h=u2sin2θ2g⇒  20=u210g or u2g=200∴   The range, R=u2×2sinθcosθg=200×2×25×5                                =200×45=160 m