Answer

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Hint: Draw the diagram of the given problem statement for a better understanding of the situation. Use the trigonometric ratios, that are $\sin \theta = \dfrac{{{\text{Opposite}}}}{{{\text{Hypotenuse}}}}$ and $\tan \theta = \dfrac{{{\text{Perpendicular}}}}{{{\text{Base}}}}$ in the physical triangle formed to find the height of the tower.

Complete step by step answer:

Let us assume the point at a foot distant from the tower be $P$.

We can draw the figure for the given scenario, where the flagstaff is fixed on the top of the tower, which is a foot distant from $P$.

The point $P$ lies in the plane of the bottom of the tower. The angle of elevation from point P to the top of the flag staff is $\alpha $ and angle of elevation from the point $P$ to the bottom of the flag staff is $\beta $.

Here $BC$ represents the height of the tower and $AB$ represents the height of the flag staff.

From the figure, in the triangle $PBC$

$\tan \beta = \dfrac{{BC}}{{PC}}$

Substituting $a$ for \[PC\] we get

$\tan \beta = \dfrac{{BC}}{a}$

On simplifying, we get

$a\tan \beta = BC$

Here $BC$ represents the height of the tower, therefore, the height of the tower is $a\tan \beta $.

Thus option D i.e. none of these is the correct answer.

Note: The diagram should be drawn correctly according to the given conditions correctly. The angle of elevation of a higher point is more than that for a lower point in the same vertical line. In a right angled triangle, the $\tan \theta $ is the equal to $\dfrac{{{\text{Perpendicular}}}}{{{\text{Base}}}}$, where perpendicular is the side opposite to the angle $\theta $, and $\sin \theta $ is the equal to $\dfrac{{{\text{Perpendicular}}}}{{{\text{Hypotenuse}}}}$, where perpendicular is the side opposite to the angle $\theta $.

Complete step by step answer:

Let us assume the point at a foot distant from the tower be $P$.

We can draw the figure for the given scenario, where the flagstaff is fixed on the top of the tower, which is a foot distant from $P$.

The point $P$ lies in the plane of the bottom of the tower. The angle of elevation from point P to the top of the flag staff is $\alpha $ and angle of elevation from the point $P$ to the bottom of the flag staff is $\beta $.

Here $BC$ represents the height of the tower and $AB$ represents the height of the flag staff.

From the figure, in the triangle $PBC$

$\tan \beta = \dfrac{{BC}}{{PC}}$

Substituting $a$ for \[PC\] we get

$\tan \beta = \dfrac{{BC}}{a}$

On simplifying, we get

$a\tan \beta = BC$

Here $BC$ represents the height of the tower, therefore, the height of the tower is $a\tan \beta $.

Thus option D i.e. none of these is the correct answer.

Note: The diagram should be drawn correctly according to the given conditions correctly. The angle of elevation of a higher point is more than that for a lower point in the same vertical line. In a right angled triangle, the $\tan \theta $ is the equal to $\dfrac{{{\text{Perpendicular}}}}{{{\text{Base}}}}$, where perpendicular is the side opposite to the angle $\theta $, and $\sin \theta $ is the equal to $\dfrac{{{\text{Perpendicular}}}}{{{\text{Hypotenuse}}}}$, where perpendicular is the side opposite to the angle $\theta $.

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