20 10 mathematics 1
I didn't know you were talking about the national volume (1). If yes, the answer is: 12. Make a plane PCD by CD, so that AB is perpendicular to the plane PCD, AB and P cross, and let the distance from P to CD be H, then there is a V-quadrilateral ABCD =1/3x2x1/2xh = 2h/3. ...