require 'matrix'

class Vector
  def scalar_triple_product(b, c)
    self.inner_product(b.cross_product c)
  end

  def vector_triple_product(b, c)
    self.cross_product(b.cross_product c)
  end
end

a = Vector[3, 4, 5]
b = Vector[4, 3, 5]
c = Vector[-5, -12, -13]

puts 
puts 
puts 
puts