Question Details

A vertical pole and a vertical tower are on the same level ground in such a way that, from the top of the pole, the angle of elevation of the top of the tower is 60° and the angle of depression of the bottom of the tower is 30°. If the height of the pole is 24 m, then find the height of the tower (in m).

Options

A

243(3+1)

B

72

C

96

D

24(31)

Show Answer

Correct Answer :

Option C

96

96

Solution :

The correct answer is 96.

To find the height of the tower, we can represent the setup using right-angled triangles based on the given angles of elevation and depression.

Step 1: Visualize the problem and label the components
Let AB represent the vertical pole of height 24 m, where A is the top and B is the bottom of the pole.
Let CD represent the vertical tower on the same level ground, where C is the top and D is the bottom of the tower.
Let x be the horizontal distance between the pole and the tower, so BD=x.
Draw a horizontal line from the top of the pole A to meet the tower CD perpendicularly at point E. Therefore, AE=BD=x and ED=AB=24 m.

The height of the tower is CD=CE+ED=CE+24.

Step 2: Find the horizontal distance using the angle of depression
From the top of the pole A, the angle of depression of the bottom of the tower D is 30°. This corresponds to the angle in the right-angled triangle AED where EAD=30°.
Using the trigonometric ratio for tangent in triangle AED:

tan(30°)=EDAE

We know that ED=24 m, AE=x, and tan(30°)=13. Substituting these values:

13=24x

Solving for x:

x=243 m

Step 3: Find the upper segment of the tower using the angle of elevation
From the top of the pole A, the angle of elevation of the top of the tower C is 60°. This corresponds to the angle in the right-angled triangle AEC where EAC=60°.
Using the trigonometric ratio for tangent in triangle AEC:

tan(60°)=CEAE

We know that AE=x=243 m and tan(60°)=3. Substituting these values:

3=CE243

Solving for CE:

CE=243×3

CE=24×3=72 m

Step 4: Calculate the total height of the tower
Now, we sum the two vertical parts of the tower to find its total height:

Height of the tower (CD)=CE+ED

CD=72+24=96 m

Thus, the total height of the tower is 96 meters.

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