How do you find the amplitude, period and graph y=2csctheta?

Feb 14, 2018

The amplitude is $2$ and the period is $2 \pi$. Please read the Explanation for graphing.

Explanation:

The amplitude of a trigonometric function is simply the number out in front of it. In $2 \csc x$, that number is $2$.

The period of a $\csc$ graph is the same period as its reciprocal function's ($\sin$), which is $2 \pi$.

The first step to graphing a reciprocal function is to expand the function with the definition of the reciprocal function. In this case:

$\csc \theta = \frac{1}{\sin} \theta$

So, to put it in the actual function:

$2 \csc x = 2 \cdot \frac{1}{\sin} x$

Now, graph the wave of $2 \sin x$ with a dotted line. The graph starts at $\left(0 , 0\right)$, has a period of $2 \pi$, and has an amplitude of $2$.

Next, mark a dot on the points where the wave reaches a maximum or a minimum (blue in the picture). Also, mark asymptotes (vertical lines) wherever the wave crosses the $x$-axis (red):

Lastly, you can draw the actual function. To do this, you have to draw figures that look like parabolas between the red lines. If the blue point in that section is above the $x$-axis, then the "parabola" is also above the $x$-axis. If it is below, then the "parabola" is below also. In the end, it looks like this (in purple):

Here's just the $2 \csc x$ graph:

I created a Desmos website with all of this information:
https://www.desmos.com/calculator/b3iqe1baxj