boost_1_45_0/libs/math/doc/sf_and_dist/equations/special_functions_blurb7.mml

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mtext>tanh</mtext>
    <mfenced>
      <mrow>
        <mi>x</mi>
      </mrow>
    </mfenced>
    <mspace width="1em"/>
    <mo>=</mo>
    <mspace width="1em"/>
    <mfrac>
      <mrow>
        <mtext>sinh</mtext>
        <mfenced>
          <mrow>
            <mi>x</mi>
          </mrow>
        </mfenced>
      </mrow>
      <mrow>
        <mtext>cosh</mtext>
        <mfenced>
          <mrow>
            <mi>x</mi>
          </mrow>
        </mfenced>
      </mrow>
    </mfrac>
  </mrow>
</math>