Question

Fie A(-1;2) B(1;-2) C(2;0) D(1;6)
a) demonstrati ca AD paralel BC
b)aflat aria lui ABCD

Answer 1

a) AD║BC ⇔ $m_A_D$=$m_{BC}$
 $m_A_D$=(Yd-Ya)/(Xd-Xa)=4/2=2
$m_{BC}$=(Yc-Yb)/(Xc-Xb)=2/1=2
=>  AD║BC