Editing Triangle wave (section)

=== Expression in trigonometric functions ===
A triangle wave with period ''p'' and amplitude ''a'' can be expressed in terms of [[sine]] and [[arcsine]] (whose value ranges from −''π''/2 to ''π''/2):
<math display="block">y(x) = \frac{2a}{\pi} \arcsin\left(\sin\left(\frac{2\pi}{p}x\right)\right).</math>
The identity <math display="inline">\cos{x} = \sin\left(\frac{p}{4}-x\right)</math> can be used to convert from a triangle "sine" wave to a triangular "cosine" wave. This phase-shifted triangle wave can also be expressed with [[cosine]] and [[arccosine]]:
<math display="block">y(x) = a - \frac{2a}{\pi} \arccos\left(\cos\left(\frac{2\pi}{p}x\right)\right).</math>