Question

The electrician has to repair an electric fault on a pole of height 4 metres.He needs to reach a point 1 metre below the top of the pole to undertake the repair work. What should be the length of the ladder that he should use,which when inclined at an angle of 60° to the horizontal would enable him to reach the required position?
[Use√3=1.73]



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Answer 1

Answer:

3.46m

Step-by-step explanation:

The perpendicular distance is (4- 1) 3m.

let the length of the ladder be x.

We have to use sin 60°.

• sin60° = opposite/ hypotenuse
• (√3)/2 = 3/x

In this case hypotenuse is x and opposite is the length of the pole.

• x = (3 × 2)/√3

By rationalising the denominator we get,

• x = (6 × √3)/(√3 × √3)
• x = (6 ×√3)/3
• x = 2√3
• x = 2 × 1.73
• x = 3.46m

Answer 2

Answer:

Let AC be the pole and BD be the ladder.

We have,

AC=4 m, AB=1 m and ∠BDC=60°And, BC=AC−AB=4−1=3 mIn ∆BDC,sin60°=BCBD⇒3√2=3BD⇒BD=3×23√⇒BD=23‾√⇒BD=2×1.73∴ BD=3.46 m

So, he should use 3.46 m long ladder to reach the required position.