Slope of a line = (y₂ - y₁)/(x₂ - x₁)
K' = y₂ - y₁ ( for E & F)
L' = x₂ - x₁ ( for E & F)
=> Slope from E to F = K'/L'
Two triangles are similar
=> K/K' = L/L' = DE/EF
=> K/K' = L/L'
=> K/L = K'/L'
=> K'/L' = K/L
Triangles are similar
K - L = K' - L'
Sufficient information is not given but from picture it is clear that slope of line = 1
=> K = L & K' = L'
hence K - L = 0 & K' - L' = 0
=> K - L = K' - L'
