An electrician has to repair an electric fault on the pole of height 5 m. He needs to reach a point 2 m 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 measure 60 to the horizontal would enable him to reach the required position.
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Let, the length of the ladder is d m.
and angle of elevation is 60 degree
So, he is 3 m above the ground.
On solving as shown in attachment we got d = 2√3 m.
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Let PR represent a pole of length 5 m.
Q is a point 2 m below the top of the pole P to undertake the repair work.
see figure, PQ = 2 m
QR = 3 m
QS is the length of ladder
angle QSR = 60°
in ∆PRS,
sin60° = QR/QS
√3/2 = 3/QS
QS = 2√3 m
hence, length of ladder = 2√3m
Q is a point 2 m below the top of the pole P to undertake the repair work.
see figure, PQ = 2 m
QR = 3 m
QS is the length of ladder
angle QSR = 60°
in ∆PRS,
sin60° = QR/QS
√3/2 = 3/QS
QS = 2√3 m
hence, length of ladder = 2√3m
Attachments:
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