(1)由题意知DE=DQ=y,∠DAE=∠DAQ
∵△ADE∽△PCE,∴DE/EC=AD/CP
∴y/(3-y)=4/x
∴y=12/(x+4)
(2)如图,过Q作QH⊥AP于H
当以4为半径的⊙Q与直线AP相切时,QH=4
则Rt△AQH≌Rt△QAD,∴∠AQH=∠DAQ
又∠QAH=2∠DAQ,∴∠QAH=2∠AQH
∴∠AQH=30°,∴AQ=QH/sin30°=8√3/3
当⊙A与⊙Q外切时,⊙A的半径=8√3/3-4
当⊙A与⊙Q内切时,⊙A的半径=8√3/3-4
(1)由题意知DE=DQ=y,∠DAE=∠DAQ
∵△ADE∽△PCE,∴DE/EC=AD/CP
∴y/(3-y)=4/x
∴y=12/(x+4)
(2)如图,过Q作QH⊥AP于H
当以4为半径的⊙Q与直线AP相切时,QH=4
则Rt△AQH≌Rt△QAD,∴∠AQH=∠DAQ
又∠QAH=2∠DAQ,∴∠QAH=2∠AQH
∴∠AQH=30°,∴AQ=QH/sin30°=8√3/3
当⊙A与⊙Q外切时,⊙A的半径=8√3/3-4
当⊙A与⊙Q内切时,⊙A的半径=8√3/3-4