Math problem on total surface area?

Question

http://img291.imageshack.us/img291/451/picture1ob3.png

the answer is: 292.93 cm2

i don't understand how to get there. help?

Answer 1

Area of top=10x5.5

=55cm²

Area of bottom=10x11

=110cm²

To find the height of the trapezium, 11-5.5=5.5. 5.5/2=2.75. The base of each of the two triangles is 2.75. height=a

base=b

hypotenuse(4)=c

a²=c²-b²

a²=16-7.5625

a²=8.4375

a=√8.4375

a=2.90473751

The height of each triangle if the trapezium is 2.90473751.

Area of front=1/2 2.90473751(5.5+11)

=1.45236875(16.5)

=23.9640844cm²

Area of back=1/2 2.90473751(5.5+11)

=1.45236875(16.5)

=23.9640844cm²

Area of side=4x10

=40cm²

Area of side=4x10

=40cm²

Surface Area=40+40+110+23.9640844+23.9640844+55

Surface Area=292.928169cm²

Answer 2

two rectangle      4*10*2=80

two rectangle  5.5*10*2=110

two trabiz    11-5.5/2=5.5/2=2.75

h^2=4^2-2.75^2=16-7.5625=      h=sqrt(8.4375)=2.904

2*s=(11+5.5)*2.904=47.928

47.928+80+110=