The angle of elevation of a cloud from a point 60 m above the su

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 Multiple Choice QuestionsShort Answer Type

171.

A man standing on the deck of a ship, which is 10 m above water level, observes the angle of elevation of the top of a hill as 60° and the angle of depression of the base of a hill as 30°. Find the distance of the hill from the ship and the height of the hill.

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172.

The angle of elevation of the top Q of a vertical tower PQ from a point X on the ground is 60o. From a point Y, 40 m vertically above X, the angle of elevation of the top Q of the tower is 45o. Find the height of the tower PQ and the distance PX. Use square root of 3 space equals 1.73

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173.

In Given figure, a tower AB is 20 m high and BC, its shadow on the ground, is m20 square root of 3 long. Find the sun's altitude.

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174. The angle of elevation of an aeroplane from a point A on the ground 60°. After a flight of 15 seconds, the angle of elevation changes to 30°. If the aeroplane is flying at a constant height of 1500 space square root of 3 space end root space straight m, find the speed of the plane in km/hr.

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 Multiple Choice QuestionsLong Answer Type

175. At a point A, 20 metres above the level of water in a lake, the angle of elevation of a cloud is 30°. The angle of depression of the reflection of the cloud in the lake, at A is 60°. Find the distance of the cloud from A.
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 Multiple Choice QuestionsShort Answer Type

176.

The ratio of the height of a tower and the length of its shadow on the ground is √3:1. What is the angle of elevation of the sun?

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177.

A moving boat is observed from the top of a 150 m high cliff moving away from the cliff. The angle of depression of the boat changes from 60° to 45° in 2 minutes. Find the speed of the boat in m/h.

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 Multiple Choice QuestionsLong Answer Type

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178.

The angle of elevation of a cloud from a point 60 m above the surface of the water of a lake is 30° and the angle of depression of its shadow in water of lake is 60°. Find the height of the cloud from the surface of the water. 


Let AB be the surface of the lake and P be the point of observation such that AP = 60 m. Let C be the position of the cloud and C be its reflection in the lake.
Then CB =
Draw PM⊥CB
Let CM = h
∴ CB = h + 60 m

In ∆CPM
tan 30 to the power of straight o space equals space CM over PM
rightwards double arrow space fraction numerator 1 over denominator square root of 3 end fraction space equals space straight h over PM
rightwards double arrow space PM space equals space square root of 3 straight h space space.... space left parenthesis straight i right parenthesis
In increment PMC comma
tan 60 to the power of straight o space equals space fraction numerator straight C apostrophe straight M over denominator PM end fraction
rightwards double arrow space tan 60 to the power of 0 space equals space fraction numerator straight C apostrophe straight B space plus BM over denominator PM end fraction
rightwards double arrow space square root of 3 space equals space fraction numerator straight h space plus 60 space straight m space plus 60 space straight m over denominator PM end fraction
rightwards double arrow space PM space equals space fraction numerator straight h space plus 120 over denominator square root of 3 end fraction space... space left parenthesis ii right parenthesis
From space equ space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis
square root of 3 straight h space equals fraction numerator straight h space plus 120 space straight m over denominator square root of 3 end fraction space

⇒ 3h = h + 120 m
⇒ 2h = 120 m
⇒ h = 60 m
CB = h + 60m = 60m + 60m = 120m
Thus, the height of the cloud from the surface of the lake is 120 m.

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 Multiple Choice QuestionsShort Answer Type

179.

As observed from the top of a 100 m high light house from the sea-level, the angles of depression of two ships are 30° and 45°. If one ship is exactly behind the other on the same side of the light house, find the distance between the two ships. [ Use √3= 1.732 ]


 Multiple Choice QuestionsMultiple Choice Questions

180.

The angle of depression of a car, standing on the ground, from the top of a 75 m high tower, is 30o. The distance of the car from the base of the tower (in m.) is

  • 25√3

  • 50√3

  • 75√3

  • 150


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