====== Angulo Mitad ======

FIXME con eso de cos2x dentro de la raiz
  * <m 15>sin{x/2} = ± sqrt{ {1-cos x}/2 }</m>
  * <m 15>cos{x/2} = ± sqrt{ {1+cos x}/2 }</m>
  * <m 15>tan{x/2} = ± sqrt{ {1-cos x}/{1+cos2x} }</m>

===== Identidades Adicionales =====

  * <m 15>tan{x/2} = csc x - cot x = {sin x}/{1 + cos x}</m>
  * <m 15>cot{x/2} = csc x + cot x = {sin x}/{1 - cos x}</m>
  * <m 15>2 csc x = tan(x/2) + cot(x/2)</m>
  * <m 15>2 | cos(x/2) | = sqrt{2 + 2 cos x}</m> | es valor absoluto FIXME
  * <m 15>2 | sin(x/2) | = sqrt{2 - 2 cos x}</m> | es valor absoluto FIXME
  * <m 15>sin{x/2} + cos{x/2} = ± sqrt{1 + sin x}</m>
  * <m 15>sin{x/2} - cos{x/2} = ± sqrt{1 - sin x}</m>

Investigar sobre radicales con el sin y el cos RUBIÑOS Trigonométria pag 304