WAEC Mathematics 2017 Paper

Concept:The angle of depression is the angle between the horizontal line from the observer's eye and the line of sight to the boat below. It can be found using the tangent ratio in a right-angled triangle.Explanation:Let the angle of depression be $x$.The vertical height of the observer above the boat is $100$ m.The horizontal distance between them is $80$ m.Using the tangent ratio:$\tan x = \dfrac{\text{opposite}}{\text{adjacent}} = \dfrac{100}{80} = 1.25$So, $x = \tan^{-1}(1.25)$$x = 51.3401^{\circ}$Correct to two decimal places, $x = 51.34^{\circ}$.Answer:C. $51.34^{\circ}$