Fourth, this article only deals with trigonometric function values when the expression in radicals is in "real" radicals – roots of real numbers. Many other trigonometric function values are expressible in, for example, cube roots of complex numbers that cannot be rewritten in terms of roots of real numbers. For example, the trigonometric function values of any angle that is one-third of an angle "θ" considered in this article can be expressed in cube roots and square roots by using the cubic equation formula to solve