sinA = cosB,A+B=90
C=90
c^2 = a^2 + b^2 = 2ab
(a-b)^2 = 0
a = b
A=B=45
a/sinA = 6 = b/sinB
a = 6sinA
b = 6sinB
S = ab/2 = 18 sinA sinB = 9 sin2B = 9