i need to figure out the size and direction of the force on each segment

http://i32.tinypic.com/1075g8g.gif

in cd segment there is a 45 degree between the electricity and magnetic field
so i need to have size 40*sin 45

why they write only 40
??

why i get a totaly differen result

notice that cd = 0.4 i + 0.4 j (m), so in the cross product with B=0.02 j (N/A.m) the j part is zero.


another way of putting it is the cd length is bigger than the bc length, that compensate the angle.

thanks