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We have this relationship
NW / NO = NO / NS
NW / 6 = 6 / 8
NW = 36 / 8 = 9/2 = 4.5
So....using the Pythagorean Theorem
WO = sqrt ( 6^2 + 4.5^2 ) = sqrt (56.25) = 7.5
So....the perimeter is
WO + NW + NS + SO =
7.5 + 4.5 + 8 + 10 =
12 + 8 + 10 =
30