so we got a rectangle base, 2 rectangle sides and 2 triangle sidess
ok so 6cm=height total
ok
so the trianglular sides
the base is4 and height is 6
2 triangles so
2 times 1/2 times 4 time 6=24 for both triangles
now the rectangle parts
the bottom bit is 4 by 12 or 48
the back one is 7 by 12 or 84
the front one is unknown because we don't know the side length of the front side (if we use pythagoran theorem and stuff we get that the side is √(65-8√13)) or about6.01, so I would say about 6)
so 6 times 12=72
total is
triangles+rectangles=
24+48+84+72=
228
about 228 square cm (if that front side length is 6)