r1 := -1/6*(4*b^2-a^2)^(1/2)*a/b/sin(phi); r2 := -1/3*(4*b^2-a^2)^(1/2)*a*c/(2*sin(phi)*b^2-sin(phi)*a^2-2*sin(phi)*c*b-( 4*b^2-a^2)^(1/2)*a*cos(phi)); r3 := 1/3*(4*b^2-a^2)^(1/2)*a*c/(2*sin(phi)*b^2-sin(phi)*a^2-(4*b^2-a^2)^(1/2) *a*cos(phi)); Sb := ((1/2*a+1/2*b+1/2*c)*(-1/2*a+1/2*b+1/2*c)*(1/2*a-1/2*b+1/2*c)*(1/2*a+1/2 *b-1/2*c))^(1/2); Aa := abs(arctan((4*b^2-a^2)^(1/2)*a/(2*b^2-a^2+2*c*b))); Ab := abs(arctan((4*b^2-a^2)^(1/2)*a/(2*b^2-a^2-4*c*b))); Ac := 1/2*Pi-arctan((2*b^2-a^2-c*b)/(4*b^2-a^2)^(1/2)/a);