1解:S△PCQ=1/2PC*QC=0.5(BC-PB)QC=0.5(8-2t)*t=4t-t^2(t≤4)
当t=4/2=2时,S△PCQ有最大值:4×2-2^2=4cm^2
2解:
S△PDQ=S矩形-S△APD-S△PBQ-S△DQC
=12*6-6AP-1/2PB*BQ-3CQ
=72-6t-0.5(6-t)×2t-3(12-2t)
=t^2-6t+36 (t≤6)
当t=6/2=3时,S△PDQ有最小值:3^2-18+36=27cm^2