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A pole is standing erect on the ground w...

A pole is standing erect on the ground which is horizontal. The tip of the poke is tied tight with a rope of length ` sqrt(12)` m to a point on the ground. If the rope is making `30^(@)` angle with the horizontal , then the height of the pole is

A

` 2 sqrt(3) m `

B

`3 sqrt(2)` m

C

3 m

D

`sqrt(3)` m

Text Solution

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The correct Answer is:
To find the height of the pole, we can use the properties of right-angled triangles and trigonometric ratios. Here’s a step-by-step solution: ### Step 1: Understand the problem We have a pole (AB) standing erect on the ground, and the tip of the pole is tied to a point on the ground (C) with a rope (AC) of length \( \sqrt{12} \) meters. The angle between the rope and the horizontal ground is \( 30^\circ \). ### Step 2: Identify the triangle In the right triangle ABC: - AB is the height of the pole (which we need to find). - AC is the length of the rope (hypotenuse), which is \( \sqrt{12} \) meters. - Angle ACB is \( 30^\circ \). ### Step 3: Use the sine function In a right triangle, the sine of an angle is defined as the ratio of the length of the opposite side to the length of the hypotenuse. Thus, we can write: \[ \sin(30^\circ) = \frac{\text{Opposite}}{\text{Hypotenuse}} = \frac{AB}{AC} \] Substituting the known values: \[ \sin(30^\circ) = \frac{H}{\sqrt{12}} \] ### Step 4: Substitute the value of \( \sin(30^\circ) \) We know that: \[ \sin(30^\circ) = \frac{1}{2} \] So, we can rewrite the equation as: \[ \frac{1}{2} = \frac{H}{\sqrt{12}} \] ### Step 5: Solve for H To find H, we can cross-multiply: \[ H = \frac{1}{2} \cdot \sqrt{12} \] Now, simplify \( \sqrt{12} \): \[ \sqrt{12} = \sqrt{4 \times 3} = 2\sqrt{3} \] Substituting this back into the equation: \[ H = \frac{1}{2} \cdot 2\sqrt{3} = \sqrt{3} \] ### Step 6: Conclusion Thus, the height of the pole is: \[ H = \sqrt{3} \text{ meters} \]
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