a) tgB = AC/AB = 1,5
ΔADC asemenea ΔABD (∡DAC ≡∡B, AD latura comuna)
AC/AB = DC/AD = AD/BD = 1,5
AD = DC/1,5 AD = 1,5BD ⇒⇒ DC/1,5 = 1,5BD ⇒⇒
⇒⇒ BD = DC/2,25 = 10/2,25 = 1000/225 = 40/9 cm
b) AB/AC = 1,2
ΔABD asemeneaΔACD (∡B = ∡DAC)
AB/AC = BD/AD = AD/DC = 1,2
AD = BD/1,2 = 1,2DC ⇒ CD = BD/1,44 = 5/1,44 = 500/144 = 125/36 cm