20 12 college entrance examination mathematics Shandong volume (science) solid geometry problem second question how to use vectors to find the coordinates of d! (where CA is the x axis, CB is the y axis and CF is the z axis) ...

The quadrilateral ABCD is an isosceles trapezoid, ABCD, ∠ DAB = 60,

Let CB = CD = 1.

∠DCB= 120

∠CDB =∠ Central Business District =30

DH= 1/2，CH= √3/2

d(？ √3/2 , - 1/2 , 0)