AB=[tex] \sqrt{(xA-xB) ^{2}+(yA-yB) ^{2} } [/tex]
[tex]5= \sqrt{(-1-4+a) ^{2}+(2-4-a) ^{2} } [/tex]
[tex]5= \sqrt{(-5+a) ^{2}+(-2-a) ^{2} } [/tex]
[tex]5= \sqrt{a ^{2}-10a+25+a ^{2}+4a+4 } [/tex]
[tex]5= \sqrt{2a ^{2}-6a+29 } [/tex]
Ridicam la patrat
25=2a²-6a+29
2a²-6a+4=0
delta=36-4*4*2
=36-32
=4
[tex]a _{1} = \frac{6-2}{4} =1[/tex]
[tex] a_{2}= \frac{6+2}{4} =2 [/tex]
