Expression 11: "x" squared plus "y" squared minus StartFraction, 1 Over StartRoot, "x" squared plus "y" squared , EndRoot , EndFraction cosine left parenthesis, "a" arctan left parenthesis, "x" , "y" , right parenthesis , right parenthesis plus cosine left parenthesis, 2 "a" arctan left parenthesis, "x" , "y" , right parenthesis , right parenthesis less than or equal to 3x2+y2−1x2+y2cosaarctanx,y+cos2aarctanx,y≤3