First of all, you have to find the area of both triangles:
[tex] \frac{bh}{2} [/tex]
[tex] \frac{4*4}{2} [/tex]
Or just 16 because there are 2 of the same triangles.
Now you have to find the area of the 3 rectangles.
The two that are in the front are 4*3 (l*h) or 12*2 (because there are 2 congruent rectangles. The area of those rectangles is 24 square mm.
Now you find the area of the back rectangle:
5.7*3 = 17.1
Finally, you add all the found numbers to figure out the surface area.
17.1 + 16 + 24 = 57.1 square millimeters.
Hope this helped,
Loafly
