Question

A(-1,2) B(4-a,4+a) lungimea AB =5, a=?

Answer 1

$AB= \sqrt{( x_{2 }- x_{1})^2 +( y_{2}- y_{1})^2$$AB= \sqrt{(4-a+1)^2+(4+a-2)^2}= \sqrt{(5-a)^2+(2+a)^2} \\ 25=25-10a+a^2+4+4a+a^2 \\ 2a^2-6a+4=0$
$a^2-3a+2=0 \\ a_{1}=1; a_{2}=2$