find the distance d (P1 P2) between the P1 and P2

Question

P1=(-1,1);P2=(1,2)

Answer 1

d = sqrt [ ( x2 - x1 ) ^ 2 + ( y2 - y1 ) ^ 2 ]

In this case :

x1 = - 1

y1 = 1

x2 = 1

y2 = 2

d = sqrt [ ( 1 - ( - 1 ) ) ^ 2 + ( 2 - 1 ) ^ 2 ]

d = sqrt [ ( 1 + 1 ) ) ^ 2 + 1 ^ 2 ]

d = sqrt [ 2 ^ 2 + 1 ]

d = sqrt ( 4 + 1 )

d = sqrt ( 5 )