A ladder rests against a wall at an angle α to the horizontal. Its foot is pulled away from the wall through a distance a, so that it slides a distance b down the wall making an angle β with the horizontal. Show that a/b=cosα-cosβ/sinβ-sinα
Answers
a/b = (Cosα - Cosβ )/(Sinβ - Sinα)
Step-by-step explanation:
Let say Ladder length = L
A ladder rests against a wall at an angle α to the horizontal.
=> Cosα = Distance of Ladder from wall / Length of Ladder
=> Distance of Ladder from wall = L Cosα
=> Sinα = Height of Ladder from wall / Length of Ladder
=> Height of Ladder from wall = L Sinα
Its foot is pulled away from the wall through a distance a
Cosβ = (L Cosα + a)/L
=> LCosβ = L Cosα + a
=> L (Cosβ - Cosα ) = a
=> L = a/(Cosβ - Cosα )
Sinβ = (L Sinα - b)/L
=> LSinβ = L Sinα - b
=> b = L (Sinα - Sinβ)
=> L = b/(Sinα - Sinβ)
a/(Cosβ - Cosα ) = b/(Sinα - Sinβ)
=> a/b = (Cosβ - Cosα ) /(Sinα - Sinβ)
=> a/b = -(Cosα - Cosβ )/(-(Sinβ - Sinα))
=> a/b = (Cosα - Cosβ )/(Sinβ - Sinα)
QED
Proved
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