Trigonometric Functions: Domain and Range

9. Trigonometric function. The graphs of the trigonometric functions were already studied in Chapter 2 of Mathematics Book I; this section simply records their domain and range for reference: $\sin x$ has domain $R$ and range $[-1,1]$; $\cos x$ has domain $R$ and range $[-1,1]$; $\tan x$ has domain $R-\left\{\pm\dfrac{\pi}2,\pm\dfrac{3\pi}2,\ldots\right\}$ (all reals except the odd multipl …