20.如图所示,在边长为3的等边三角形ABCABCABC中,AD→=23AC→\overrightarrow{AD}=\frac{2}{3}\overrightarrow{AC}AD=32AC,且点PPP在以ADADAD的中点OOO为圆心,OAOAOA为半径的半圆上,若BP→=xBA→+yBC→\overrightarrow{BP}=x\overrightarrow{BA}+y\overrightarrow{BC}BP=xBA+yBC,则?(?(?( )))