You need to break this into smaller shapes. This shape consists of 4 smaller shapes: 3 triangles and 1 rectangle.
Formulas:
Triangle: A = 1/2 bh
Rectangle: A= bh
Let's start with the triangle on top with the points B, C and D.
Base = 6
Height = 3
A = 1/2 (6)(3)
Multiply base by height
A = 1/2 (18)
Multiply.
A= 9
The triangle on the left:
Base= 4
Height = 4
A= 1/2 (4)(4)
A= 1/2 (16)
A= 8
The triangle on the right:
Base= 2
Height= 4
A= 1/2 (2)(4)
A= 1/2 (8)
A= 4
The rectangle in the middle:
Base= 6
Height=4
A= (6)(4)
A= 24
Now add all the areas together:
9 + 8 + 4 + 24 = 45 cm²
Hope this helps! :)