1. The problem is to plot graphs of trigonometric functions. 2. The main trigonometric functions to consider are sine ($y=\sin x$), cosine ($y=\cos x$), and tangent ($y=\tan x$). 3. These functions are periodic with period $2\pi$ for sine and cosine, and $\pi$ for tangent. 4. The sine function oscillates between $-1$ and $1$, starting from $0$ at $x=0$. 5. The cosine function also oscillates between $-1$ and $1$, starting from $1$ at $x=0$. 6. The tangent function has vertical asymptotes where cosine is zero, specifically at $x=\frac{\pi}{2} + k\pi$, $k$ integer. Final note: These functions are fundamental in trigonometry and appear in many applications such as physics and engineering.