WMTC 2013 problem!

in tetrahedron P-BCD, PB=PC=PD=BC= sqrt{3} . if angle BCD = 90 degrees, and length of CD is 1, find the tangent of the planar angle B-PD-C.

also i dont know how to use the LaTeX... :( also what is a planar angle, i found this question on an test, i know the answer but i did not know how to solve it

Moderator's edit:

In a tetrahedron $PBCD$ , $PB=PC=PD=BC = \sqrt3$ , if $\angle BCD = 90^\circ$ , and the length of $CD = 1$ , find the tangent of the planar angle $\angle BPDC$ .