Expression 7: left brace, "x" greater than or equal to 0 : left parenthesis, "x" squared plus "y" squared , right parenthesis cos left parenthesis, "n" arctan left parenthesis, StartFraction, "y" Over "x" , EndFraction , right parenthesis plus phi , right parenthesis , right brace greater than or equal to "z" Has graph.x≥0:x2+y2cosnarctanyx+ϕ≥z
7
Expression 8: left brace, "x" less than 0 : left parenthesis, "x" squared plus "y" squared , right parenthesis cos left parenthesis, "n" arctan left parenthesis, StartFraction, "y" Over "x" , EndFraction , right parenthesis plus pi plus phi , right parenthesis , right brace greater than or equal to "z" Has graph.x<0:x2+y2cosnarctanyx+π+ϕ≥z