cos3

cos(5 pi / 6)

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <csymbol cd="transc1">cos</csymbol>
    <apply>
      <csymbol cd="arith1">divide</csymbol>
      <apply>
        <csymbol cd="arith1">times</csymbol>
        <cn>5</cn>
        <csymbol cd="nums1">pi</csymbol>
      </apply>
      <cn>6</cn>
    </apply>
  </apply>
</math>

Author: Design Science, Inc. (E. Cannon, E. Tabacman, R.Miner)