Respostas

2014-08-27T16:32:19-03:00
A (........4;........Y) 
B (.......-1;........7) 
AB² = (4+1)²+(y-7)² = 5² 
25+(y-7)² = 25 
(y-7)²= 0 
y-7 = 0 
y = 7