Let AB = h m be the height of the tower; B and C are two points such that ∠ACB = 30°; ∠ADB = 45° and CD = x m (say) From right triangle ABD, tan‌45°=
h
BD
⇒BD=hm; Again from right triangle ABC ta‌30°=
h
h+x
⇒h+x=√3h ∴ x = (1.73 – 1)h = 0.73h Now, 0.73h m covered in 12 min Hence, h m covered in