Consider the cube in the first octant with sides OP, OQ and OR of length 1, along the x-axis, y-axis and zaxis, respectively, where O(0, 0, 0) is the origin. Let S(1/2,1/2,1/2) be the centre of the cube and T be the vertex of the cube opposite to the origin O such that S lies on the diagonal OT. If vector p=vector SP, vector q=vector SQ, vector r=vector SR and vector t=vector ST, then the value of |vector((pxq)x(rxt))| is--------.
