(1)当t4时,P在BA上,OQ=2t,高为3-[t-4]*sinA=27/5-3t/5,则S=2t*(27/5-3t/5)/2=-3t²/5+27t/5,开口向下的抛物线,在t=-27/5/(2*(-3/5))=4.5时,有最大值=12.15
(2)当t
(1)当t4时,P在BA上,OQ=2t,高为3-[t-4]*sinA=27/5-3t/5,则S=2t*(27/5-3t/5)/2=-3t²/5+27t/5,开口向下的抛物线,在t=-27/5/(2*(-3/5))=4.5时,有最大值=12.15
(2)当t