I.p:{-fie ΔABC si M∈AB , N∈AC ⇔AM=2CM, AB=8CM si NC=7,5cm}
C.{AN=?}
Dem.{-folosind teorema lui Thales in ΔABC obtinem:
AM/AB=AN/AC -dar AM=2CM si AB=8CM si observam ca AC=AN+NC adica AC=AN+7,5cm si inlocuim: 2CM/8CM=AN/AN+7,5 ⇔1/4=AN/AN+7,5 ⇒ 4AN=AN+7,5 ⇒3AN=7,5 ⇒ AN=2,5cm}