title: Why are tan, acos and asin methods missing from Ruby's BigMath module?
body: <p>I noticed that the <a href="https://ruby-doc.org/stdlib-3.1.2/libdoc/bigdecimal/rdoc/BigMath.html" rel="nofollow noreferrer">BigMath module</a> from Ruby standard library contains several methods to do trigonometry with <code>BigDecimal</code> numbers, such as <code>BigMath.cos</code>.</p>
  <p>However, tangent (<code>tan</code>), arccosine (<code>acos</code>) and arcsine (<code>asin</code>) methods are not implemented in the module. They are available from the <code>Math</code> module, which deals with <code>Float</code> numbers, but not <code>BigDecimal</code>.</p>
  <p>I am wondering what prevented from implementing them in the first place, and what it would take to implement them now.</p>
  <p>Thank you.</p>