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An electrician must reach a point $1.3\mathrm{m}$ below the top of a pole of height $5\mathrm{m}$. A ladder is placed at $60^{\circ}$ to the horizontal. Approximately what length of ladder is required? 
A$3.7\mathrm{m}$
B$4.28\mathrm{m}$
C$5.00\mathrm{m}$
D$6.41\mathrm{m}$
Answer & Solution
Correct answer: B. $4.28\mathrm{m}$
The required vertical height is $5-1.3=3.7\mathrm{m}$. If $L$ is the ladder length, then $\sin 60^{\circ}=\frac{3.7}{L}$. Hence $L=\frac{3.7\times 2}{\sqrt{3}}\approx 4.28\mathrm{m}$.
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