kill(all)$

van=facebook.com/LearningCalculus$

M:matrix([x-6,x^2+3,2],[3,x+2,x^2-6],[2,x^2-6,x+3]);

factor(determinant(M));

S:fullratsimp(realpart(append(solve(-(x^2+x-1),x),solve(x^3-9*x^2+73,x))))$

S[1];S[2];S[3];S[4];S[5];

substitute(Pi,%pi,substitute(arctan,atan,S));