Question

What's the distance between the points (a, b) and (–a, –b)?

Answer 1

d= $\sqrt{(a-(-a) )^{2} +( b-(-b)^{2} )} \\ = \sqrt{ (a+a)^{2} + ( b+b)^{2} } \\ = \sqrt{ 2a^{2}+ 2b^{2} }$

Answer 2

please show the picture