Answer:
Step-by-step explanation:
Givens
A = -2,1
B= 1,-1
Solution
AB = sqrt( (-2 - -1)^2 + (1 - -1)^2 )
AB = sqrt( (-2 + 1)^2 + (1 + 1)^2 )
AB = sqrt( (-1)^2 + 2^2)
AB = sqrt (1 + 4)
AB = sqrt(5)