func (d Decimal) Cos() Decimal {
	return Decimal{
		decimal: d.decimal.Cos(),
		vars:    cos + leftParen + d.vars + rightParen,
		formula: cos + leftParen + d.formula + rightParen,
	}
}
// Cos returns the cosine of the radian argument x.
Cos returns the cosine of the radian argument x.
// Cos returns the cosine of the radian argument x .
func (d Decimal) Cos() Decimal {
	return Decimal{
		decimal: d.decimal.Cos(),
		vars:    cos + leftParen + d.vars + rightParen,
		formula: cos + leftParen + d.formula + rightParen,
	}
}
func ( d Decimal ) Cos ( ) Decimal { return Decimal { decimal : d . decimal . Cos ( ) , vars : cos + leftParen + d . vars + rightParen , formula : cos + leftParen + d . formula + rightParen , } }
Cos returns the cosine of the radian argument x.
Cos returns the cosine of the radian argument x .