A man on the deck of a ship, 16 m above water level observes that the angles of elevation and depression respectively of the top and bottom of a cliff are 60∘ and 30∘. Calculate the distance of the cliff from the ship and height of the cliff.
Let AB be the deck of the ship above the water level and DE be the cliff.
Now,
AB=16 m such that CD=16 m and ∠BDA=30∘ and ∠EBC=60∘.
If AD=x m and DE=h m, then CE=(h−16) m.
In the right △BAD, we have:
ABAD=tan30∘=1√3
⇒16x=1√3
⇒x=16√3=27.68 m
In the right △EBC, we have:
ECBC=tan60∘=√3
⇒(h−16)x=√3
⇒h−16=x×√3
⇒h−16=16√3×√3=48 [∵x=16√3]
⇒h=48+16=64 m
∴ Distance of the cliff from the deck of the ship =AD=x=27.68 m
And,
Height of the cliff =DE=h=64 m