Question

An electrician has to repair an electric falut on a pole of height 4 metres, He needs to reach a point 1 metre below the top of pole to undertake the repair work. What should be the length of the ladder that the should use, which when inclined at an angle of ${60}^{\circ }$ to the horizontal would enable him to reach the required position ? [Use $\sqrt{3}=\mathrm{1.732.}$]

Answer 1

Given the height of the pole = 4 m

So AD = 4 m

BD = AD - AB = 4 - 1 = 3 m

Since pole is vertical to ground, $\angle BDC={90}^o$

In right-angled triangle, $△BCDsinC=\frac{BD}{BC}sin{60}^o=\frac{3}{BC}\frac{\sqrt{3}}{2}=\frac{3}{BC}BC=\frac{3\times 2}{\sqrt{3}}=2\sqrt{3}BC=2\times 1.73=3.46m$

Length of the ladder = 3.46 m