For comparison with other CAS choose from: Axiom Derive Macsyma Maple Reduce
    Solve[ x ^8 - 8x^7 + 34x^6 - 92x^5 + 175x^4 - 236x^3 +
           226x^2 - 140x + 46 == 0 ]
           4 - Sqrt[16 - 8 (5 - Sqrt[-3 - 4 Sqrt[3]])]
    {{x -> -------------------------------------------},
                                4
           4 + Sqrt[16 - 8 (5 - Sqrt[-3 - 4 Sqrt[3]])]
     {x -> -------------------------------------------},
                                4
           4 - Sqrt[16 - 8 (5 + Sqrt[-3 - 4 Sqrt[3]])]
     {x -> -------------------------------------------},
                                4
           4 + Sqrt[16 - 8 (5 + Sqrt[-3 - 4 Sqrt[3]])]
     {x -> -------------------------------------------},
                                4
           4 - Sqrt[16 - 8 (5 - Sqrt[-3 + 4 Sqrt[3]])]
     {x -> -------------------------------------------},
                                4
           4 + Sqrt[16 - 8 (5 - Sqrt[-3 + 4 Sqrt[3]])]
     {x -> -------------------------------------------},
                                4
           4 - Sqrt[16 - 8 (5 + Sqrt[-3 + 4 Sqrt[3]])]
     {x -> -------------------------------------------},
                                4
           4 + Sqrt[16 - 8 (5 + Sqrt[-3 + 4 Sqrt[3]])]
     {x -> -------------------------------------------}}
                                4
    Solve[ Log[ ArcCos[ ArcSin[x ^(2/3)-b]- 1]]+ 2 == 0, x ]
                  3      2              -2
    {{x -> -Sqrt[b  + 3 b  Sin[1 + Cos[E  ]] +
                           -2  2                -2  3
          3 b Sin[1 + Cos[E  ]]  + Sin[1 + Cos[E  ]] ]},
                 3      2              -2
     {x -> Sqrt[b  + 3 b  Sin[1 + Cos[E  ]] +
                          -2  2                -2  3
         3 b Sin[1 + Cos[E  ]]  + Sin[1 + Cos[E  ]] ]}}
 Simplify[%]
                                 1   2  3
    {{x -> -Sqrt[(b + Sin[2 Cos[----] ]) ]},
                                   2
                                2 E
                                1   2  3
     {x -> Sqrt[(b + Sin[2 Cos[----] ]) ]}}
                                  2
                               2 E