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A man of height 6 ft. observes the top o...

A man of height 6 ft. observes the top of a tower and the foot of the tower at angles of `45^@` and `30^@` of elevation and depression respectively. The height of the tower is

A

16.39 m

B

14.59 m

C

14.29 m

D

none of these

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The correct Answer is:
To find the height of the tower, we can follow these steps: ### Step 1: Understand the Problem We have a man who is 6 feet tall. He observes the top of a tower at an angle of elevation of 45 degrees and the foot of the tower at an angle of depression of 30 degrees. We need to find the height of the tower. ### Step 2: Define Variables Let: - \( h \) = height of the tower (in feet) - The height of the man = 6 feet - The distance from the man to the base of the tower = \( x \) ### Step 3: Set Up the Right Triangles 1. **For the angle of elevation (45 degrees)**: - The height from the man's eye level to the top of the tower is \( h - 6 \) (since the man is 6 feet tall). - According to the tangent function: \[ \tan(45^\circ) = \frac{h - 6}{x} \] Since \( \tan(45^\circ) = 1 \): \[ 1 = \frac{h - 6}{x} \implies h - 6 = x \quad \text{(Equation 1)} \] 2. **For the angle of depression (30 degrees)**: - The height from the man's eye level down to the foot of the tower is 6 feet. - According to the tangent function: \[ \tan(30^\circ) = \frac{6}{x} \] Since \( \tan(30^\circ) = \frac{1}{\sqrt{3}} \): \[ \frac{1}{\sqrt{3}} = \frac{6}{x} \implies x = 6\sqrt{3} \quad \text{(Equation 2)} \] ### Step 4: Substitute Equation 2 into Equation 1 From Equation 1, we have: \[ h - 6 = x \] Substituting \( x = 6\sqrt{3} \): \[ h - 6 = 6\sqrt{3} \] Adding 6 to both sides: \[ h = 6\sqrt{3} + 6 \] ### Step 5: Calculate the Height of the Tower Now we can calculate \( h \): - First, we need to find the value of \( 6\sqrt{3} \): \[ \sqrt{3} \approx 1.732 \implies 6\sqrt{3} \approx 6 \times 1.732 \approx 10.392 \] Thus, \[ h \approx 10.392 + 6 \approx 16.392 \text{ feet} \] ### Final Answer The height of the tower is approximately **16.39 feet**. ---
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OBJECTIVE RD SHARMA ENGLISH-HEIGHTS AND DISTANCES-Exercise
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  4. If the elevation of the sun is 30^@ , then the length of the shadow c...

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  16. A tower 50 m high , stands on top of a mount, from a point on the grou...

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  17. A person on a ship sailing north sees two lighthouses which are 6 km a...

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  19. A vertical lamp-post, 6m high, stands at a distance of 2 m from a wall...

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