A light house which faces the north , throws light beam in the shape of a fan from north-east to north-west in the sky. On a ship a man that is going to west looks the light for the first time. When he is 8km distance from the light house and continuously looks it for 15√2 minutes, then find out the speed of the ship in km/h.
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Given:-
- distance between man and light house = 8km.
To Find:-
- the speed of the ship in km/h.
step-by-step solution:-
→ O is a light house which faces north. when ship reaches pint A then it looks light, where OA = 8 km.
→When the ship reaches at point B after 15√2 minutes, then it happens to see the light.
So, OB = OA = 8 km
From right angled ΔBCO.
⟶ Sin 45° = BC/BO = 1/√2
⟶ BC/8 = 1/√2
⟶ BC = 8/√2 = 4√2
So,
⟶ AB = 2BC = 4 × 2√2
⟶ 8√2km.
Speed = Distance/time
⟶ 8√2/15√2 km/min
⟶ 8/15 × 60 km/h
⟶ 32km/h
Hence, speed of aeroplane = 30 km/h.
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