Answer:
At any given moment, the red ant's coordinates may be written as (a, a) where a > 0. The red ant's distance from the anthill is 
 . The black ant's coordinates may be written as (-a, -a) and the black ant's distance from the anthill is
 . The black ant's coordinates may be written as (-a, -a) and the black ant's distance from the anthill is 
 . This shows that at any given moment, both ants are
 . This shows that at any given moment, both ants are 
 units from the anthill.
 units from the anthill.
Explanation:
Given: 
red ant's coordinates written as (a,a)
black ant's coordinates are written as (-a, -a) 
To find:
The distance of red and black ants from anthill
Solution:
Compute the distance of red ant from the anthill using distance formula
d (red ant) = 

 = 

 = 

 = 
 
 
So distance of red ant from anthill is 
 
 
Compute the distance of black ant from the anthill using distance formula
d (black ant) = 

 = 

 = 

 = 

 = 
 
 
So distance of black ant from anthill is 
 
 
Hence both ants are 
 units from the anthill.
 units from the anthill.