Length of the walking trail is 12 units.
Step-by-step explanation:
Three points of the walking trail are R(-1,4),S(5,4)and T(5,-2). so we have to calculate the distance between points R and S and also between S and T. finding the sum of these distances would give the distance of the walking trail.
The equation to calculate the distance between two points
and
is

RS=

=

ST=
=

length of the walking trail = RS+ST= 6+6 =12