Graph of cosecant: y = csc x
The cosecant graph is 1/sin x: alternating upward and downward U-shapes that touch y = 1 and y = −1 at the peaks and troughs of the sine wave, with vertical asymptotes at every multiple of π.
Key features
- Domain
- All real x except x = nπ
- Range
- y ≤ −1 or y ≥ 1
- Period
- 2π
- Vertical asymptotes
- x = nπ
- Local minima
- y = 1 at x = π/2 + 2nπ
- Local maxima
- y = −1 at x = 3π/2 + 2nπ
- Symmetry
- Odd: csc(−x) = −csc x
- y-intercept
- None: x = 0 is an asymptote
- Derivative
- −csc(x)cot(x)
- Antiderivative
- −ln(|csc(x)+cot(x)|)+C
Derivative and antiderivative from the calculator’s algebra system. Domain, range and asymptotes are stated for real x.
What the graph of csc x looks like
Cosecant is to sine what secant is to cosine. Each upward U sits on a peak of sin x and touches y = 1 there; each downward U sits on a trough and touches y = −1. Wherever sin x = 0, at every multiple of π, there is an asymptote.
Because sin x is odd, so is csc x: the graph is symmetric about the origin, with an upward branch just right of zero and a downward branch just left of it.
The secant graph shifted right by π/2 is exactly the cosecant graph, since csc x = sec(x − π/2).
Points of interest
Found numerically to about twelve digits in the window −7 ≤ x ≤ 7, then shown in exact form where one exists.
- x-intercepts (roots)
- None in this window
- Local maxima
- (−1.5708, −1), (4.7124, −1)
- Local minima
- (−4.7124, 1), (1.5708, 1)
- Inflection points
- None in this window
There are no roots: csc x is never zero.
Table of values
A few points to plot, with exact values where they are simple.
| x | y = csc x |
|---|---|
| π/6 | 2 |
| π/4 | √2 |
| π/3 | 2√3/3 |
| π/2 | 1 |
| 2π/3 | 2√3/3 |
| 5π/6 | 2 |
| 3π/2 | −1 |
How to graph csc x by hand
- 1Lightly sketch y = sin x.
- 2Draw dashed asymptotes at every zero of sin x: x = 0, ±π, ±2π.
- 3Draw an upward U on each peak of the sine curve and a downward U on each trough.
- 4Make every branch approach its two asymptotes.
Transformations
How the graph moves when you change the formula. The original is csc x in blue.
y = csc(2x)Period π: asymptotes every π/2.y = 0.5csc(x)Vertical squash: branches turn at y = ±0.5.y = csc(x) + 1Shifted up 1: the gap in the range is now 0 < y < 2.
Frequently asked questions
What is the range of csc x?
Where are the asymptotes of the cosecant graph?
Is csc x odd or even?
What is the derivative of csc x?
Related graphs
Period 2π, amplitude 1, zeros at every multiple of π.
1/cos x: U-shaped branches, never between −1 and 1.
Period π, asymptotes at multiples of π, always decreasing.
Period π, asymptotes at π/2 + nπ, always increasing.
A hyperbola with asymptotes along both axes.
(eˣ − e⁻ˣ)/2: odd, increasing, through the origin.
Change the window, add sliders for a, b, h and k, trace the curve with your keyboard, or overlay its derivative.