②PQ∑AB, then q is the midpoint (0,3) of OB,

③Q is on the x axis, OP/OQ=OB/OA,

4/OQ=6/8，OQ= 16/3，

∴Q( 16/3,0)

④PQ⊥AB, q is QR⊥Y axis in R,

PQ/OB=AQ/AO=AP/AB，PQ/6=AQ/8=4/ 10，

PQ= 12/5，AQ= 16/5，

∫QR * AP = AQ * PQ，QR =( 12/5× 16/5)÷4 = 48/25 = 1.92

AR=√(AQ^2-QR^2)=64/25=2.56，

∴OR=8-2.56=5.44，

∴Q( 1.92,5.44)。