A 1.8 m tall man is standing at some distance from a building. The angle of elev

Sail E0 Webinar

Question

A 1.8 m tall man is standing at some distance from a building. The angle of elevation from his eyes to the top of the building increases from $30^{\circ}$ to $60^{\circ}$ as he walks 20 m towards the building. Find the height of the building (in m).

Options:

A . 10 m

B . 20

\sqrt{3}

m

C . 20 m

D . (10

\sqrt{3}

+ 1.8) m

Answer: Option D
:
D

The situation can be represented by the figure above.
$t a n (∠ A C B) = \frac{A B}{B C} \Rightarrow B C = \frac{A B}{t a n 60^{\circ}} . . . . . (1) t a n (∠ A D B) = \frac{A B}{B D} \Rightarrow t a n 30^{\circ} = \frac{A B}{B C + C D} \Rightarrow B C + C D = \frac{A B}{t a n 30^{\circ}} . . . . . (2) on subtracting equation(1) from (2) \Rightarrow C D = \frac{A B}{t a n 30^{\circ}} - \frac{A B}{t a n 60^{\circ}} \Rightarrow A B = 10 \sqrt{3}$
Hence, the height of the building is
= AB + BG = $(10 \sqrt{3} + 1.8) m .$

Was this answer helpful ?

Next Question

Submit Solution

More Questions on This Topic :

Question 1. A kite is attached to a string of length 20√3m is tied to a pole on the level ground. If the string of the kite makes....the kite is flying at a height of 20 m.

Question 2. A tower is 100√3 m high. Find the angle of elevation of its top from a point 100 m away from its foot.....

Question 3. The string of a kite is 100m long and it makes an angle of 60∘ with the horizontal. Find the height of the kite fro....ground, assuming that there is no slack in the string.

Question 4. The angle of elevation of the top of a tower from a point on the ground, which is 30m away from the foot of the tower is....the tower is 30∘. Find the height of the tower.

Question 5. Two towers A and B are standing at some distance apart. From the top of tower A, the angle of depression of the foot of....of tower A in terms of ‘h’ is _____ m

Question 6. Find the angle of elevation of the sun when the shadow of a 10m long pole is 10√3 m.....

Question 7. A circus artist is climbing a 20m long rope, which is tightly stretched and tied from the top of a vertical pole to the ....made by the rope with the ground level is 30∘ .

Question 8. The angle of elevation of the top of a tree from a point A on the ground is 60∘ . On walking 20 m away from point A, ....elevation changes to 30∘. Find the height of the tree.

Question 9. The tops of two poles of height 14 m and 20 m are connected by a wire which makes an angle of 30° with the horizontal. ....with the horizontal. The length of the wire is _____m.

Question 10. From the top of a cliff 25m high the angle of elevation of a tower is found to be equal to the angle of depression to t....of the tower. The height of the tower is ___.

Chapter 1 - GLOBAL STEEL SCENARIO & INDIAN STEEL INDUSTRY Part 1 : (13-04-2024) INDUSTRY AND COMPANY AWARENESS (ICA)

Direction Sense Test Part 1 Reasoning (Hindi)

Chapter 1 - RMHP / OHP / OB & BP Part 1 : (14-02-2024) GPOE

Cube & Cuboid Part 1 Reasoning (Hindi)

Data Interpretation (DI) Basic Concept Reasoning (Hindi)

Counting Figures Part 1 Counting Of Straight Lines Reasoning (Hindi)

Sail E0 free webinar Webinars

Real Numbers Part 7 Class 10 Maths

Real Numbers Part 1 Class 10 Maths

Polynomials Part 1 Class 10 Maths

GPOE / GPA Combined 1 Free Mock Test SAIL JO E-0 2024

Chapter 3.1 : INTRODUCTION Chapter 3 : Sinter Plant SAIL E0 - GPOE/GPA 2024

Chapter 2.3 : COAL HANDLING PLANT - Set 1 Chapter 2 : Coke Ovens and Coal Chemicals SAIL E0 - GPOE/GPA 2024

Chapter 1.1 : INTRODUCTION Chapter 1 : Raw Material Handling Plant SAIL E0 - GPOE/GPA 2024

DSP Combined 1 Free Revision Test SAIL JO E-0