code: function triangleArea(a,b,c){
      return (((b[0] - a[0])*(c[1] - a[1]))-((c[0] - a[0])*(b[1] - a[1])));
  }
docs: Get the area of a triangle spanned by the three given points. Note that the area will be negative if the points are not given in counter-clockwise order.
  @static
  @method area
  @param  {Array} a
  @param  {Array} b
  @param  {Array} c
  @return {Number}