Scale factor of 1/2, means shrink lines to half
Then
A'B'= AB/2
Trace the 2 diagonals
Find point of intersection of AC ,and BD
DRAWING
Find distance from point (-1,2) to A,B,C and D
and reduce to half
A= (-10,2)
Distance to A =
X'= (-10-1)/ 2 = -5.5
Y' = (2--2) /2= 4/2 = 2
Then
A'= (-5.5,2)
Distance to B
B= (7,8)
Distance to B=
X'= (7-1)/2= 3
Y'= (8--2) /2= 10/2= 5
Therefore
B'= (3, 5)
Distance to C
C= (5,-8)
X'= (5-1)/2= 4/2= 2
Y'=(-8--2)/2 = -6/2= -3
Then
C'= (2,-3)
Distance to D
D= (-3,-10)
X'=(-3-1)/2= -4/2=-2
Y'=(-10--2)/2 = -8/2= -4
Then also
D'= (-2,-4)
Now we have the 4 coordinates of new figure A'B'C'D'