ABvector=AOvector+OBvector=OBvector-OAvector=(2-4)i+(3-2)j=-2i+j
|-2i+j|=√((-2)²+1²)=√(4+1)=√5
analog
BCvector=OCvector-OBvector=...=(6-2)i+(6-3)j=4i+3j
|4i+3j|=√(4²+3²)=...=5
CA vector=OAvector-OCvector=(4-6)i+(2-6)j= -4i-4j
|-4i-4j|=√((-4)²+(-4)²)=√(16+16)=...=4√2
la b) procedezi analog
!! ca idee, |ABvector|=|BAvector|
si planul verctorial, cu "i" si "j" ⇔planul cartezian, cel cu x si y
unde prin "⇔" poti intelege "aceeasi Marie cu alta palarie", matematic se zice "izomorfism" de la izos= aceeasi si morphos=forma
