chapter 10 . math form 4 :(

Chapter 10 : Angles of Elevation and Depression






10.1 : Angles of Elevation and angles of depression 

*Horizontal line,angle of elevation and angle of depression 

• The horizontal line is the line at the eye level of the observer and parallel to the flat ground or plane.The line is always perpendicular to the object that is being observed.

• The angle of elevation of an object B from a lower point A is the angle measured upwards from the horizontal line,AC through point A to line of sight,AB.

                       

• The angle of depression of an object r from a higher point Q is the angle measured downwards from the horizontal line QP through point Q to the line of sight,QR .

                              




*Representing a particular situation involving the angle of elevation and the angle of depression using diagrams

The diagrams involving the angle of elevation and the angle of depression.

• Determine the position of the observer and the object being observed.
• Draw the horizontal line from the eye of the observed.
• Draw the line of sight.
• Draw the line from the object perpendicular to the horizontal line.Mark the right angle.
• Mark the angle of elevation or depression.

*Solving problems

Trigonometry ratios such as sine,cosine and tangent and Pythagoras' theorem are often used in solving problems involving angle of elevation and angle of depression.