Question

ΔABC, A(1,a), B(2,-1), C(3,2), D(1,-2). A=? stiind ca AB paralel cu CD

Answer 1

AB || CD => $m_{AB} = m_{CD}$ (panta lui AB este egala cu panta lui CD)
$\frac{y_{B}- y_{A} }{x_{B}- x_{A}} = \frac{y_{D}- y_{C} }{x_{D}- x_{C}}$
$\frac{-1-a }{2-1} = \frac{-2-2}{1-3}$
$\frac{-1-a }{1} = \frac{-4}{-2}$
-1-a=2
a=-3 => A(1,-3)

Sper ca ai inteles rezolvarea.