Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 3 - No. 46)
Which of the following statements are true about the angles of elevation and depression?
They are always equal in magnitude.
The angle of depression is always smaller than the angle of elevation.
They are formed with respect to the horizontal.
They can only be used in right-angled triangles.
Explicación
Angles of elevation and depression, viewed between parallel lines, are equal and both refer to a horizontal plane.