In elementary algebra, transforming a polynomial into a product (factoring) is a resource of enormous practical importance: $x^2 - 2x = x(x - 2)$ highlighting $x^2 - 4 = (x + 2)(x - 2)$ difference of squares $x^2 \pm 4x + 4 = (x \pm 2)^2$ perfect square trinomials $x^3 + 8 = (x + 2)(x^2 - 2x + 4)$ sum of cubes $x^3 - 8 = (x - 2)(x^2 + 2x + 4)$ difference of cubes $x^3 \pm 3x^2 + 3x \pm 1 = (x \pm 1)^3$ perfect cubes We will often apply these features to trigonometry, with transformations like $\operatorname{sen}^2 x - 2\operatorname{sen} x = \operatorname{sen} x(\operatorname{sen} x - 2)$ and $\operatorname{sen}^2 x - \cos^2 x = (\operatorname{sen} x + \cos x)(\operatorname{sen} x - \cos x)$. In addition to algebraic resources, trigonometry has formulas that allow you to complete a factorization — in the example above, also factor $\operatorname{sen} x + \cos x$ and $\operatorname{sen} x - \cos x$.