Question : The angles of elevation of a pole from two points which are 75 m and 48 m away from its base are $\alpha$ and $\beta$, respectively. If $\alpha$ and $\beta$ are complementary, then the height of the tower is:
Option 1: 54.5 m
Option 2: 61.5 m
Option 3: 60 m
Option 4: 50 m
Correct Answer: 60 m
Solution : Given, BD = 48 and BC = 75 In △ABD, $\tan β = \frac{AB}{BD}$ ⇒ $\tan β = \frac{AB}{48}$ ⇒ $AB = 48 \tan β$ ...........(1) In △ABC, $\tan α = \frac{AB}{BC}$ ⇒ $AB = 75 \tan α$ .............(2) Multiply by equation (1) from equation (2), ⇒ $AB^2 = 48 × 75 × \tan α × \tan β$ As we know, $α + β = 90°$ ⇒ $\tan α \tan β = 1$ ⇒ $AB = \sqrt{48 × 75}$ ⇒ $AB = \sqrt{16 × 3 × 3 × 25}$ ⇒ AB = 4 × 3 × 5 = 60 m Hence, the correct answer is 60 m.
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Question : A pole stands vertically on a road, which goes in the north-south direction. P and Q are two points towards the north of the pole, such that $P Q=b$, and the angles of elevation of the top of the pole at $P, Q$ are $\alpha, \beta$ respectively. Then the height of the pole is:
Option 1: $\frac{b}{\tan \beta+\tan \alpha}$
Option 2: $\frac{b}{\tan \beta-\tan \alpha}$
Option 3: $\frac{b}{\cot \beta-\cot \alpha}$
Option 4: $\frac{\mathrm{b} \tan \alpha}{\tan \beta}$
Question : The angles of elevation of the top of a tower from two points on the ground at distances 32 m and 18 m from its base and in the same straight line with it are complementary. The height (in m) of the tower is____________.
Option 1: 20
Option 2: 24
Option 3: 16
Option 4: 28
Question : Two points A and B are on the ground and on opposite sides of a tower. A is closer to the foot of the tower by 42 m than B. If the angles of elevation of the top of the tower, as observed from A and B are 60° and 45°, respectively, then the height of the tower is closest to:
Option 1: 87.6 m
Option 2: 98.6 m
Option 3: 88.2 m
Option 4: 99.4 m
Question : A clock tower stands at the crossing of two roads which point in the north-south and the east-west directions. $P, Q, R$, and $S$ are points on the roads due north, east, south, and west respectively, where the angles of elevation of the top of the tower are respectively, $\alpha, \beta, \gamma$ and $\delta$. Then $\left(\frac{\mathrm{PQ}}{\mathrm{RS}}\right)^2$ is equal to:
Option 1: $\frac{\tan ^2 \alpha+\tan ^2 \beta}{\tan ^2 \gamma+\tan ^2 \delta}$
Option 2: $\frac{\cot ^2 \alpha+\cot ^2 \beta}{\cot ^2 \gamma+\cot ^2 \delta}$
Option 3: $\frac{\cot ^2 \alpha+\cot ^2 \delta}{\cot ^2 \beta+\cot ^2 \gamma}$
Option 4: $\frac{\tan ^2 \alpha+\tan ^2 \delta}{\tan ^2 \beta+\tan ^2 \gamma}$
Question : A pole of length 7 m is fixed vertically on the top of a tower. The angle of elevation of the top of the pole observed from a point on the ground is 60° and the angle of depression of the same point on the ground from the top of the tower is 45°. The height (in m) of the tower is:
Option 1: $7(2 \sqrt{3}-1)$
Option 2: $\frac{7}{2}(\sqrt{3}+2)$
Option 3: $7 \sqrt{3}$
Option 4: $\frac{7}{2}(\sqrt{3}+1)$
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