The distance between point on the ground from the top of the building is 396 meter, if the building is 280 m high and The angle of depression from the top of a building to a point  on the ground is 45 degrees.
Step-by-step explanation:
The given is,
         The angle of depression from the top of a building to a point  on the ground is 45 degrees.
         Height of the building is 280 meter.
Step: 1
         Given diagram is a right angled diagram,
         For right angle triangle,
               90° = 45° + 45°  Â
                   = 90° Â
         Trignometric ratio,
              sin ∅ = [tex]\frac{Opp}{Hyp}[/tex]....................(1)
        For the above ratio take the bottom angle, that is angle of depression from the top of a building to a point  on the ground is 45 degrees.
         Where, Opp side = 280 meters
                Hyp side = x
                      ∅ = 45°
         Equation (1) becomes,
                 sin 45° = [tex]\frac{280}{x}[/tex]
             0.70710678 =  [tex]\frac{280}{x}[/tex]
                      x =  [tex]\frac{280}{0.70710678}[/tex]
                      x = 395.979
        Distance between point on the ground from the top of the building,  x ≅ 396 meter                        Â
        Trignometric ratio,
                   cos ∅ = [tex]\frac{Adj}{Hyp}[/tex]
                  Cos 45 = [tex]\frac{Adj}{396}[/tex]
                     Adj = (0.70710678)(396)
       Bottom length, Adj = 280 meter
Result:
      The distance between point on the ground from the top of the building is 396 meter.
