已知x2+y2+2x﹣6y+10=0,求x+y的值.
解:x2+y2+2x-6y+10=0,(x+1)2+(y-3)2=0,x+1=0,y-3=0,解得:x=-1,y=3.则:x+y=﹣1+3=2.
挂钟分针的长10cm,经过45分钟,它的针尖转过的弧长是____ cm.
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