Here's another way...but it looks a bit longer than CPhill's!
First let's extend line AB .
Then....
Draw a line perpendicular to AB that goes through point C .
Draw a line perpendicular to AB that goes through point E .
Draw a line parallel to AB (and perpendicular to the previous two lines) that goes through point D .
Now let's label these new points of intersection W, X, Y, and Z , like the picture,
and put the information from the problem.
∠EAZ = ∠CBY = 180° - 120° = 60°
Since triangles AEZ and BCY are 30-60-90 triangles where the side across from the 90° angle is 2....
the side across from the 30° angle = 2/2 = 1
the side across from the 60° angle = √3
And...
WD + DX = 2 + 1 + 1 And WD = DX , so we can substitute WD in for DX .
WD + WD = 2 + 1 + 1
2WD = 4
WD = 2
Now we can use the Pythagorean theorem to find CX .
22 + CX2 = 42
4 + CX2 = 16 Subtract 4 from both sides of the equation.
CX2 = 12 Take the positive square root of both sides.
CX = 2√3
And.....
area of ABCDE = area of WXYZ - 2(area of △EDW) - 2(area of △AEZ)
= (width)(length) - 2(1/2)(base)(height) - 2(1/2)(base)(height)
= (2 + 2)(2√3 + √3) - 2(1/2)(2)(2√3) - 2(1/2)(1)(√3)
= 12√3 - 4√3 - √3
= 7√3 square units