41.2 cm
Explanation:
subtract the y's and x's to get the distances
left & right sides are hypotenuses
top :
10 - (-2) = 12
bottom :
5 - (-7) = 12
left :
3 - (-4) = 7 = height
-7 -(-2) = -5 = 5 = base
pythagorean theorem
49 + 25 = 74
square root of 74 = 8.6
right :
same
perimeter :
12 + 12 + 8.6 + 8.6 = 41.2