B
calculate the slopes m of the 2 lines using the gradient formula
m = (y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁ ) = C(- 2, 4) and (x₂, y₂ ) = D(0, - 4 )
= = = - 4
repeat with (x₁, y₁ ) = F(- 4, 0 ) and (x₂, y₂ ) = G(4, 2 )
= = =
The 2 lines are perpendicular because their slopes are negative reciprocals