# How do you find the amplitude and period of y=0.7tan(0.3x-1.8)?

The amplitude does not exist/is undefined or however you want to say it. The period is $\frac{20 \pi}{3}$.
The equation can be written as $a \sin \left(b \left(x - c\right)\right) + d$. For sin and cos (but not tan) $| a |$ is the amplitude, $\frac{2 \pi}{|} b |$ is the period, and $c$ and $d$ are the phase shifts. $c$ is the phase shift to the right (positive $x$ direction) and $d$ is the phase shift up (positive $y$ direction). In this case, you need to take out a $.3$ inside of the parentheses. You then get $0.7 \tan \left(0.3 \left(x - 0.6\right)\right)$. Now just follow the model above; the period is $\frac{2 \pi}{.3}$ or $\frac{20 \pi}{3}$.
Note that tangent graphs do not have altitudes (they go from $- \infty$ to $\infty$).