The function of 1 * tan(2x) is equal to (2 * tan[x])/(1 - tan^2[x]). Because a value multiplied by one is equal to itself, the tangent function with the variable x can be solved using the double-angles identity rule for trigonometric functions.
The identity of a trigonometric function refers to properties of the function that are true regardless of the input values. Using the double-angle identity to evaluate tan(2x) gives the (sin[2x]/cos[2x])/cos^2(x), since the tangent function is equal to the ratio of the sine to the cosine. The sin(2x) = 2 * sin(x) * cos(x), while cos(2x) = cos^2(x) ? sin^2(A) = 2 * cos^2(x) -1 = 1 - 2 * sin^2(x).