题目

阅读理解Teens take a standCOP 26 was held in Glasgow, Scotland from Oct 31 toNov 12. It's the United Nations climate change conference (会议) for dealingwith global warming.Many world leaders took part in the event. But there were also lots of teenagers from different countries there to make their voices heard. At 15, my friend Chelsea Liang from Edinburgh was one of the young participants at COP 26. I was able to ask her some questions about her experience there.Liang participated as a junior representative (代表) of C Team, a non-governmental organization, which organized all the eve已知抛物线经过点A（，0）、B（m，0）（m>0），且与y轴交于点C．   ⑴求a、b的值（用含m的式子表示）  ⑵如图所示，⊙M过A、B、C三点，求阴影部分扇形的面积S（用含m的式子表示）； ⑶在x轴上方，若抛物线上存在点P， 使得以A、B、P为顶点的三角形与相似，求m的值．