Question

An
electrician has to repair an electric fault on a pole of height 4m. He needs
to reach a point 1.3m 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 $60o$
to the
horizontal would enable him to reach the required position?

Answer 1

Correct Answer - (i) $3.46 m$ , (ii) $40 m$ , (iii) $20 m$
Let AB be the electric pole such that AB = 4 m . Let C be a point 1m below B.
Then, $AC = 4 m - 1 m = 3 m$.
Let OC be the ladder.Then, $angleAOC = 60^(@)$
Let OC = x metres.
From right $DeltaOAC$, we have
$(OC)/(AC) = cosec 60^(@) rArr x/3 = 2/(sqrt(3)) rArr x = (6)/(sqrt(3)) xx (sqrt(3))/(sqrt(3)) = 2sqrt(3)$.
$rArr x = (2 xx 1.73) = 3.46$
Hence the length of the ladder is $3.46 m$.