Answer:
Perpendicular
Step-by-step explanation:
Calculate the slopes m of the segments using the slope formula.
m = 
Parallel lines have equal slopes
The product of the slopes of perpendicular lines equals - 1
(x₁, y₁ ) = A(0, 0) and (x₂, y₂ ) = B(e, f)
= 
= 
Repeat with (x₁, y₁ ) = C(0, e) and (x₂, y₂ ) = D(f, 0)
= 
= - 
Thus AB and CD are perpendicular since × - = - 1
<em>AC bisects ∠BAD, => ∠BAC=∠CAD ..... (1)</em>
<em>thus in ΔABC and ΔADC, ∠ABC=∠ADC (given), </em>
<em> ∠BAC=∠CAD [from (1)],</em>
<em>AC (opposite side side of ∠ABC) = AC (opposite side side of ∠ADC), the common side between ΔABC and ΔADC</em>
<em>Hence, by AAS axiom, ΔABC ≅ ΔADC,</em>
<em>Therefore, BC (opposite side side of ∠BAC) = DC (opposite side side of ∠CAD), since (1)</em>
<em />
Hence, BC=DC proved.
