(2)
點(diǎn)
是直線BC上方拋物線上一個(gè)動(dòng)點(diǎn),過點(diǎn)
作
軸的垂線交直線BC于點(diǎn)
, 過點(diǎn)
作
軸的垂線,垂足為點(diǎn)
, 請(qǐng)?zhí)骄?img class="mathml" src="http://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmi%3ED%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmi%3EE%3C%2Fmi%3E%3C%2Fmath%3E" style="max-width:100%;vertical-align: middle;">是含有最大值?若有最大值,求出最大值及此時(shí)
點(diǎn)的坐標(biāo);若沒有最大值,請(qǐng)說明理由.