Sketching of \(y=a\tan \left( bx \right)\)

Sketching of \(y=a\tan \left( bx \right)\)

\(y=\tan x\)

Tangent has no amplitude, maximum or minimum. Its range is all real numbers.

Function\(0^\circ\) (\(0\))\(90^\circ\) (\(\frac{\pi}{2}\))\(180^\circ\) (\(\pi\))\(270^\circ\) (\(\frac{3\pi}{2}\))\(360^\circ\) (\(2\pi\))
\(\tan x\)

\(y=a\tan(bx)\), \(a,b>0\)

\(T=\dfrac{180^\circ}{b}\text{ or}\hspace{0.5em}\dfrac\pi b\)

\(\text{Zeros:}\hspace{0.5em}x=\dfrac{k\pi}{b}\qquad\text{Asymptotes:}\hspace{0.5em}x=\dfrac{\pi/2+k\pi}{b}\quad(k\in\mathbb Z)\)

EquationMidlineAmplitudeMaximum and minimumPeriod
\(y=3\tan 2x-1\)
FunctionPeriod (degrees)Period (radians)
\(y=5\tan 3x\)
\(y=3\tan 2x\)
\(y=\tan\frac{3x}{4}\)
\(y=\tan(\pi x)\)

Draw dashed vertical asymptotes, mark the zeros midway between them, then sketch an increasing branch in each interval. Branches never cross vertical asymptotes.

Example: \(y=\tan\left(\dfrac32x\right)\), \(0\le x\le2\pi\)

Period \(\dfrac{2\pi}{3}\). Zeros: \(0,\dfrac{2\pi}{3},\dfrac{4\pi}{3},2\pi\). Vertical asymptotes: \(\dfrac\pi3,\pi,\dfrac{5\pi}{3}\). Each branch increases between its asymptotes.

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