Solution: Given: θ = angle between Sun's rays (incident on mirror) and Earth's surface = 69.0o    α = angle between plane of mirror and vertical line = ?   We also have following facts: Let i = angle of incidence Let r = angle of reflection Then we have: i = r Angle α  is defined as: α = angle between plane of mirror and vertical line Angle α is also given by: α = angle between plane of mirror and incident ray This relation follows from the following facts: ... See the full answer