Angles of elevation and depression Quiz 1

Question 1

An UFO is hovering 800 m above a river. It is observed by the passengers of a boat as they look upwards at an angle of $$30{}^	ext{o}$$. Thirty seconds later, passengers look up at an angle of $$60{}^	ext{o}$$ to see the UFO. How far did the boat go in 30 seconds?

Accepted Answer

$$923.7m$$

Answer

$$981.7m$$

Answer

$$920.7m$$

Answer

$$933.7m$$

Question 2

A flag pole is erected at the exact middle of a square shaped stadium. If the angle of elevation of the top of the pole from a corner of the stadium is $$30{}^	ext{o}$$, find the angle of elevation of the top of the pole from the midway of any side (boundary) of the stadium.

Accepted Answer

$${{	an }^{-1}}\left( \dfrac{\sqrt{2}}{\sqrt{3}} ight)$$

Answer

$${{	an }^{-1}}\left( \dfrac{1}{\sqrt{2}} ight)$$

Answer

$${{45}^{0}}$$

Answer

$${{	an }^{-1}}\sqrt{2}$$

Question 3

Two persons started riding their bikes simultaneously from a common starting point A, and travelled in two different straight ways which subtend an angle of $$60{}^	ext{o}$$ at the starting point A. If the speeds of the first and the second persons are 60 kmph and 80 kmph respectively, what will be the shortest distance between their positions after 2 hours from their simultaneous start?

Accepted Answer

$$40\sqrt{13}km$$

Answer

$$140km$$

Answer

$$20\sqrt{26}km$$

Answer

$$36\sqrt{15}km$$

Question 4

A structure stands on the bank of a river. A man looks out from a corner of the building's roof at the foot of an electric post on the opposite bank. What is the width of the river if the angle of depression of the foot of the light post at your eye is 60° and the height of the building is 14 metres?

Accepted Answer

8.082meters

Answer

20.784 meters

Answer

16.84 meters

Answer

10.982 meters

Question 5

From his college rooftop, Athul saw a bird flying at $$30{}^	ext{o}$$ angle of elevation near a well, Athul found that the reflection of the bird in the well water can be seen at $$60{}^	ext{o}$$ angle of depression. If the height of his college is 200 m, then how high was the bird flying from the ground?

Accepted Answer

400 m

Answer

260 m

Answer

1600 m

Answer

840 m