hmm, trailing arms use one large arm per wheel. the arm is attached to the car in front of the wheel. The arm travels up and down but not side to side, nor does it rotate. When the car is turning body roll also changes the angle of the arm. Because the arm cannot move independantly of the chassis the wheels camber changes as well. Think understeer when you think of trailing arms.
They also have semi-trailing arms, basically arms mounted at an angle instead of straight up and down. These are better because the angle of the arms cancels out the body roll from the chassis and you get a neutral handling car, but because the arm is at an angle, when it moves up and down the wheels camber changes.
Are you asking this to try to find a car to buy? Or just curious?
Here is a pict I stole
the front of the car is the top of the picture, your looking down on the suspension just like you were standing on the roof of the car, facing the front.