Question 35


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Jambmaths question: 

A cliff on the bank of a river is 300 metres high. If the angles of depression of a point on the opposite side of the river is 60o. Find  the width of the river.

Jamb Maths Solution: 

$\begin{align}  & \angle DAB=\angle ABC\text{    (Alternate angles)} \\ & \frac{AC}{BC}=\tan {{60}^{\circ }} \\ & \frac{300}{BC}=\sqrt{3} \\ & BC=\frac{300}{\sqrt{3}}=\frac{300\times \sqrt{3}}{\sqrt{3}\times \sqrt{3}}=100\sqrt{3}m \\\end{align}$

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