How to make a trapezoid? and how to make this phone stand more stable?

Hi,

During extrusion, you can set the angle:

i want the center of sketch line in center of the rectangle, then i can scale the one face of the rectangle to be mm precise

thats way too unprecise, and only works in direction of extrusion.

You can use Move, or Translate tools to get the sketch to the desired location. Sometimes Translate is more helpful, you can select the mid point of the sketch, to move to the center point of the face.