arccos4

- ( arccos ( 2 x + pi / 2)

W3C sample	WIRIS
	$-\arccos (2x+\frac{\pi }{2})$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <minus/>
    <apply>
      <arccos/>
      <apply>
        <plus/>
        <apply>
          <times/>
          <cn>2</cn>
          <ci>x</ci>
        </apply>
        <apply>
          <divide/>
          <cn>&#x003C0;</cn>
          <cn>2</cn>
        </apply>
      </apply>
    </apply>
  </apply>
</math>

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