表达式9: "l" left parenthesis, "a" , "b" , right parenthesis equals left parenthesis, "b" . "x" minus "a" . "x" , right parenthesis squared plus left parenthesis, "b" . "y" minus "a" . "y" , right parenthesis squaredla,b=b.x−a.x2+b.y−a.y2
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表达式10: left parenthesis, "l" left parenthesis, "O" , "A" , right parenthesis minus "l" left parenthesis, "O" , "B" , right parenthesis , right parenthesis squared plus left parenthesis, "l" left parenthesis, "O" , "B" , right parenthesis minus "l" left parenthesis, "O" , "C" , right parenthesis , right parenthesis squared tilde 0lO,A−lO,B2+lO,B−lO,C2~0
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trace circle
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表达式12: "l" left parenthesis, "O" , left parenthesis, "x" , "y" , right parenthesis , right parenthesis equals "l" left parenthesis, "O" , "A" , right parenthesislO,x,y=lO,A
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表达式13: polygon left parenthesis, "O" , "A" , "O" , "B" , "O" , "C" , right parenthesispolygonO,A,O,B,O,C
