Graphs of sec(x), cosec(x) and cot(x)
In a nutshell
By using the graphs of y=sin(x), y=cos(x) and y=tan(x), you can sketch a useful plot of the reciprocal graphs y=cosec(x), y=sec(x) and y=cot(x).
The functions
Recall that
cosec(x)sec(x)cot(x)=sin(x)1=cos(x)1=tan(x)1
This helps when using the plots of the graphs of y=sin(x), y=cos(x) and y=tan(x).
The graphs
When a graph has an x-intercept, it follows that the reciprocal of that graph has an asymptote, and vice versa. Below, the graphs are given using degrees. The shapes would be the same for radians, but the x-axes would be in radians.
y=cosec(x)
The domain of this function is all the real numbers, excluding integer multiples of 180 (in degrees) or multiples of π (in radians). At these points, there are asymptotes. The range is y≤−1 or 1≤y. As with y=sin(x), it has a period of 360 (if in degrees) or 2π (if in radians). Notice that if you drew y=sin(x) on the same grid, the peaks of y=cosec(x) would meet the troughs of y=sin(x), and vice versa.
y=sec(x)
The domain of this function is all the real numbers, excluding odd integer multiples of 90 (in degrees) or odd multiples of 2π (in radians). At these points, there are asymptotes. The range is y≤−1 or 1≤y. As with y=cos(x), it has a period of 360 (if in degrees) or 2π (if in radians). Notice that if you drew y=cos(x) on the same grid, the peaks of y=sec(x) would meet the troughs of y=cos(x), and vice versa.
y=cot(x)
The domain of this function is all all real numbers, excluding integer multiples of 180 (in degrees) or integer multiples of π (in radians): this is where there are asymptotes. The range is all real numbers.