∵角A,B,C成等差数列
∴2B=A+C
∵A+B+C=π ∴B=π/3
∵sinA=√2/2 ∴A=π/4 ∴C=5π/12
∵a=√2
∴b=a*sinB/sinA=√3
∴SΔABC=absinC/2=(3+√3)/4