In trapezium $$ABCD$$ has $$AD$$ parallel to $$BC,AC$$ and $$BD$$ intersect at $$P$$. If $$\dfrac {[ADP]}{[BCP]}=\dfrac {1}{2}$$, find $$\dfrac {[ADP]}{[ABCD]}$$. (Here the notion $$[P_{1}...P_{n}]$$ denotes the area of the polygon ) $$[P_{1}...P_{n}]$$
D
$$2(\sqrt {3}-\sqrt {2})$$
Correct option is A. $$2-\sqrt {3}$$