In rectangle ABCD, AD=3. P is on AB, and DB and DP divide ∠ADC into three angles such that ∠ADP:∠PDB:∠BDC=1:2:3. What is the perimeter of △BDP?
3(6+3−1)
3(6+3+1)
3(6+2−1)
6+33
36+6