Labelling
Let AE = h = DF
Let EB = z
Let AD = x
EF = x - z (use subtraction)
angle EBA = 90 - θ (angle sum of straight line)
Therefore, angle BAE = θ (angle sum of triangle)
Angle EAD is a right angle by the way we constructed it, therefore, angle BAD = 90-theeta
Therefore, angle BDA =...