sinA+cosA=根号下2/2
√2sin(A+π/4)=√2/2
sin(A+π/4)=1/2
A+π/4=5π/6
A=7π/12
面积=1/2×AC×ABsinA=1/2×2×3×sin7π/12
=3sin7π/12
=3(√6+√2)/4