To solve the terminal arm word problem, the correct approach involves calculating the principal angle using the formula $$\theta=\pi-\left(\tan^{-1}\left(-\frac{5}{2}\right)+\pi\right)=\tan^{-1}\left(\frac{5}{2}\right)$$. The primary trigonometric functions related to the angle subtended by the arm and the positive x-axis can be expressed as $$\beta=\pi-\theta$$, with the relationships $$\sin(\beta)=\sin(\theta)$$, $$\cos(\beta)=-\cos(\theta)$$, and $$\tan(\beta)=-\tan(\theta)$$. For those unfamiliar with LaTeX, a comprehensive tutorial is available to help users get started. Understanding these concepts will facilitate solving similar problems effectively.