Answer: 81.1 cm^2
This value is approximate.
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Work Shown:
area = 0.5*side1*side2*sin(included angle)
area = 0.5*AB*AC*sin(A)
area = 0.5*11*18*sin(55)
area = 81.0960523846101
area = 81.1 cm^2
The cm^2 refers to "square cm".
Notice that the angle must be between the two sides, hence the "included".