Răspuns :
AD = AD
∡AMD = ∡NAD (bis)
AM = AN (ip) => (LUL) Δ AMD = Δ AND a)
Δ AMD = Δ AND => MD = ND b)
Δ AMD = Δ AND => ∡AMD = ∡AND c)
AM = AN
AB = AC (diferenta) => MB = NC d)
∡DMB = 180 - ∡AMD
∡CND = 180 - ∡AND
∡AMD = ∡AND => ∡DMB = ∡CND e)
MD = ND
BD = DC
MB = NC => (LLL) => ΔBMD = ΔCND f)
∡AMD = ∡NAD (bis)
AM = AN (ip) => (LUL) Δ AMD = Δ AND a)
Δ AMD = Δ AND => MD = ND b)
Δ AMD = Δ AND => ∡AMD = ∡AND c)
AM = AN
AB = AC (diferenta) => MB = NC d)
∡DMB = 180 - ∡AMD
∡CND = 180 - ∡AND
∡AMD = ∡AND => ∡DMB = ∡CND e)
MD = ND
BD = DC
MB = NC => (LLL) => ΔBMD = ΔCND f)