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The tops of two poles of height 22 m and 31 m are connected by a wire. If the wire makes an angle of 60° with the horizontal, then the length of the wire (in m) is:

Solution

✅ Correct Option: 1

The two poles have heights of 22 m and 31 m respectively. A wire connects their tops at an angle of 60° with the horizontal.

The height difference between the poles is:

31−22=931 - 22 = 9 m


When viewed from the side, the wire forms a right-angled triangle where:

  • The vertical side (height difference) = 9 m
  • The hypotenuse = length of the wire
  • The angle with horizontal = 60°

The wire makes a 60° angle with the horizontal, and the vertical height difference (opposite side) is 9 m.

Using the sine ratio:

sin⁡(60°)=oppositehypotenuse\sin(60°) = \dfrac{\text{opposite}}{\text{hypotenuse}}

sin⁡(60°)=9wire length\sin(60°) = \dfrac{9}{\text{wire length}}


Since sin⁡(60°)=32\sin(60°) = \dfrac{\sqrt{3}}{2}:

32=9wire length\dfrac{\sqrt{3}}{2} = \dfrac{9}{\text{wire length}}

wire length×3=18\text{wire length} \times \sqrt{3} = 18

wire length=183\text{wire length} = \dfrac{18}{\sqrt{3}}


Rationalizing the denominator:

wire length=183×33\text{wire length} = \dfrac{18}{\sqrt{3}} \times \dfrac{\sqrt{3}}{\sqrt{3}}

wire length=1833\text{wire length} = \dfrac{18\sqrt{3}}{3}

wire length=63\text{wire length} = 6\sqrt{3} m

Therefore, the length of the wire is 636\sqrt{3} m.

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