We can choose : A ( -3, 1 ) and C ( 3, - 1 ).
So AC is a diagonal of the rectangle ABCD;
The formula for a distance between two points:
\(d = \sqrt{( x_{2}- x_{1}) ^{2} +(y _{2} -y _{1} ) ^{2} } \\ d(AC)= \sqrt{(-3-3)^{2} +(-1-1) ^{2} } = \\ = \sqrt{36+4} =\)
=√40 = 6.32455 ≈ 6.3
Answer: B ) 6.3
