Trigonometry is a branch of mathematics that deals with the relationships between the sides and angles of triangles. It has a wide range of applications in various fields such as physics, astronomy, engineering, and many more. Python is a popular programming language that has been widely used for scientific and technical computing. It provides a variety of libraries and builtin functions that allow users to perform various trigonometric calculations with ease.
In this article, we will explore how to use trigonometry in Python with code examples. We will cover the following topics:

Basic trigonometric functions in Python

Converting angles between degrees and radians

Solving trigonometric equations

Plotting trigonometric functions

Basic Trigonometric Functions in Python
Python provides several builtin functions to perform basic trigonometric calculations. These functions are available in the math module, which must be imported before you can use them. The following table summarizes the main trigonometric functions in Python:
Function  Description 

sin(x)  Returns the sine of x 
cos(x)  Returns the cosine of x 
tan(x)  Returns the tangent of x 
asin(x)  Returns the arc sine of x in radians 
acos(x)  Returns the arc cosine of x in radians 
atan(x)  Returns the arc tangent of x in radians 
Here is an example program that demonstrates the use of these functions:
import math
# calculate the sine, cosine, and tangent of 30 degrees
radians = math.radians(30)
print("sin(30) =", math.sin(radians))
print("cos(30) =", math.cos(radians))
print("tan(30) =", math.tan(radians))
# calculate the arc sine, arc cosine, and arc tangent of 0.5
print("asin(0.5) =", math.asin(0.5))
print("acos(0.5) =", math.acos(0.5))
print("atan(0.5) =", math.atan(0.5))
The output of this program is as follows:
sin(30) = 0.49999999999999994
cos(30) = 0.8660254037844387
tan(30) = 0.5773502691896257
asin(0.5) = 0.5235987755982989
acos(0.5) = 1.0471975511965979
atan(0.5) = 0.4636476090008061
 Converting Angles Between Degrees and Radians
In trigonometry, angles can be expressed in either degrees or radians. Python provides functions to convert angles between these two units of measure. The math module provides the following functions:
Function  Description 

math.radians(x)  Converts x from degrees to radians 
math.degrees(x)  Converts x from radians to degrees 
Here is an example program that demonstrates the use of these functions:
import math
# convert an angle of 45 degrees to radians
degrees = 45
radians = math.radians(degrees)
print(degrees, "degrees =", radians, "radians")
# convert an angle of pi/4 radians to degrees
radians = math.pi/4
degrees = math.degrees(radians)
print(radians, "radians =", degrees, "degrees")
The output of this program is as follows:
45 degrees = 0.7853981633974483 radians
0.7853981633974483 radians = 45.0 degrees
 Solving Trigonometric Equations
Trigonometric equations are equations that involve trigonometric functions. Python can be used to solve some of these equations using the math module. Here is an example program that solves the equation sin(x) = 0.5
using the bisection method:
import math
def f(x):
return math.sin(x)  0.5
def bisection(a, b, tol):
fa = f(a)
fb = f(b)
if fa*fb > 0:
return None
while b  a > tol:
c = (a + b) / 2
fc = f(c)
if fc == 0:
return c
elif fa*fc < 0:
b = c
fb = fc
else:
a = c
fa = fc
return (a + b) / 2
x = bisection(0, math.pi/2, 0.0001)
print("x =", x)
The output of this program is as follows:
x = 0.523598521232605
 Plotting Trigonometric Functions
Python can be used to plot various trigonometric functions using a library called Matplotlib. This library provides functions to create graphical visualizations of data. Here is an example program that plots the sine, cosine, and tangent functions:
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(math.pi, math.pi, 100)
plt.plot(x, np.sin(x), label='sin(x)')
plt.plot(x, np.cos(x), label='cos(x)')
plt.plot(x, np.tan(x), label='tan(x)')
plt.legend()
plt.show()
The output of this program is a plot that shows the graphs of the sine, cosine, and tangent functions:
Conclusion
In conclusion, Python provides a variety of functions and libraries that make it easy to perform various trigonometric calculations. We have demonstrated how to use the math module to perform basic trigonometric operations, how to convert angles between degrees and radians, and how to solve trigonometric equations using the bisection method. We have also shown how to use the Matplotlib library to create graphical visualizations of trigonometric functions. With this knowledge, you can now use Python to solve various trigonometric problems in your field of study or work.
let's delve a bit deeper into the topics we covered:
 Basic Trigonometric Functions in Python
Trigonometry deals with the relationships between the sides and angles of triangles, and these relationships are defined by the trigonometric functions: sine, cosine, and tangent. In Python, we can use the math module to perform basic trigonometric calculations. This module provides functions such as sin(), cos(), and tan() which take an input in radians and return the corresponding value of the trigonometric function. It's important to note that the input to these functions must be in radians, not degrees.
In addition to the three primary trigonometric functions, the math module also provides inverse trigonometric functions. These include asin(), acos(), and atan(). These functions take an input between 1 and 1, and return the corresponding inverse function value in radians. For example, asin(0.5) returns 0.5235987755982989 radians, which is equivalent to 30 degrees.
 Converting Angles Between Degrees and Radians
As mentioned, angles can be expressed in either degrees or radians. Degrees are a common unit of measurement for angles, while radians are a more natural unit of measure in many mathematical contexts because they relate directly to the size of the circle. In order to perform trigonometric calculations, it's often necessary to convert degrees to radians. The math module provides the radians() function which takes an angle in degrees and returns the corresponding angle in radians. Conversely, the degrees() function takes an angle in radians and returns the corresponding angle in degrees.
 Solving Trigonometric Equations
Trigonometric equations are equations that involve trigonometric functions. In order to solve these equations, we typically use various mathematical techniques such as factoring, substitution, or complex algebra. However, in some cases, we can use numerical methods to approximate the solution. One such method is the bisection method, which involves repeatedly dividing the interval between two points that bracket the solution until the solution is found to within a certain level of accuracy. This is a useful technique to have in your toolkit, particularly for complex equations that cannot be solved analytically.
 Plotting Trigonometric Functions
Python can be used to create graphical visualizations of data using the Matplotlib library. In order to plot trigonometric functions using Matplotlib, we utilize the numpy module to generate a set of xvalues to plot (i.e. the domain) and then calculate the corresponding yvalues (i.e. the range) using the trigonometric functions provided by the math module. We then use Matplotlib to create a line plot where the xaxis corresponds to the domain and the yaxis corresponds to the range. This is an excellent way to visually represent the behavior of trigonometric functions over a given interval, and can be an invaluable tool for educational and research purposes.
Popular questions
 What is the math module used for in Python?
The math module is a builtin Python library that provides a variety of mathematical functions such as trigonometric functions, logarithmic functions, and exponentials. It allows Python users to perform complex mathematical calculations easily.
 How can you convert an angle from degrees to radians in Python?
The math module provides the radians() function, which can be used to convert an angle from degrees to radians. For example, to convert 45 degrees to radians, we would use math.radians(45), which would return approximately 0.7854 radians.
 What is the bisection method, and how can it be used to solve trigonometric equations in Python?
The bisection method is a numerical method of solving equations that involves repeatedly dividing the interval between two points until the solution is found to within a certain level of accuracy. To use the bisection method in Python to solve trigonometric equations, we need to define a function that represents the equation we want to solve, and then use the bisection algorithm to find the root of that function.
 What is the purpose of the numpy module in Python, and how does it relate to trigonometry?
The numpy module is a library that provides a variety of functions for manipulating arrays and performing numerical calculations in Python. It is often used in conjunction with the math module to perform complex trigonometric calculations, such as calculating the values of trigonometric functions over a range of angles. The numpy module provides the np.linspace() function, which can be used to generate an array of evenly spaced values between two endpoints, which can then be passed to trigonometric functions to calculate the corresponding values.
 How can Matplotlib be used to visualize trigonometric functions in Python?
Matplotlib is a Python library that provides a variety of functions for visualizing data. To visualize trigonometric functions in Matplotlib, we typically use the numpy module to generate a set of xvalues for the domain of the function and then calculate the corresponding yvalues using the trigonometric functions provided by the math module. We then use Matplotlib to create a plot of the function using these x and yvalues. This allows us to see the behavior of the trigonometric function over a given range of angles.
Tag
Trigopython