Summarize this article:
104 LearnersLast updated on September 10, 2025
Properties of Trigonometric Functions
Trigonometric functions have several unique properties that are fundamental in simplifying mathematical problems related to angles and periodic phenomena. These properties assist students in analyzing and solving problems related to oscillations, waveforms, and other periodic functions. The properties of trigonometric functions include periodicity, symmetry, and specific values at notable angles. Let's learn more about the properties of trigonometric functions.
What are the Properties of Trigonometric Functions?
The properties of trigonometric functions are essential for understanding and working with angles and periodic functions. These properties are derived from the principles of trigonometry. There are several key properties of trigonometric functions, and some of them are mentioned below:
Property 1: Periodicity Trigonometric functions such as sine and cosine have a periodic nature, repeating their values over specific intervals. For example, the sine and cosine functions have a period of \(2\pi\).
Property 2: Symmetry The sine function is odd, meaning \(\sin(-x) = -\sin(x)\), while the cosine function is even, meaning \(\cos(-x) = \cos(x)\).
Property 3: Specific Values Trigonometric functions have specific values at notable angles, such as 0, 30, 45, 60, and 90 degrees.
Property 4: Range The range of the sine and cosine functions is \([-1, 1]\).
Property 5: Pythagorean Identity The Pythagorean identity states that \(\sin^2(x) + \cos^2(x) = 1\).
Tips and Tricks for Properties of Trigonometric Functions
Students often confuse or overlook the properties of trigonometric functions. To avoid such confusion, consider the following tips and tricks:
- Periodicity: Students should remember that trigonometric functions repeat their values over specific intervals. The sine and cosine functions have a period of \(2\pi\).
- Symmetry: Remember the symmetry properties: sine is odd, and cosine is even. This helps in simplifying trigonometric expressions.
- Specific Values: Familiarize yourself with the specific values of trigonometric functions at notable angles to quickly solve problems.
- Range Awareness: Understand that the range of sine and cosine is \([-1, 1]\), which helps in verifying results.
- Pythagorean Identity: Use the identity \(\sin^2(x) + \cos^2(x) = 1\) to simplify expressions and solve equations.
Confusing Periods of Different Functions
Students should remember that different trigonometric functions have different periods. For example, the period of tangent is \(\pi\), whereas sine and cosine have a period of \(2\pi\).
Mistake 1
Misunderstanding Symmetry Properties
Students should be aware that sine is an odd function (\(\sin(-x) = -\sin(x)\)) and cosine is an even function (\(\cos(-x) = \cos(x)\)).
Mistake 2
Incorrectly Using Specific Values
Students should practice remembering the specific values of trigonometric functions at key angles like 0, 30, 45, 60, and 90 degrees.
Mistake 3
Forgetting the Pythagorean Identity
Students must remember the Pythagorean identity: \(\sin^2(x) + \cos^2(x) = 1\), as it is fundamental in trigonometry.
Mistake 4
Ignoring the Range
Students should keep in mind the range of sine and cosine functions is \([-1, 1]\), which is crucial for checking the validity of results.
Mistake 5
Solved Examples on the Properties of Trigonometric Functions
Find the value of \(\sin(90^\circ) + \cos(0^\circ)\).
The value is 2.
Problem 1
\(\sin(90^\circ) = 1\) and \(\cos(0^\circ) = 1\). Therefore, \(\sin(90^\circ) + \cos(0^\circ) = 1 + 1 = 2\).
What is the period of the sine function?
Explanation
The period is \(2\pi\).
Problem 2
The sine function repeats its values every \(2\pi\) radians, hence its period is \(2\pi\).
Determine if the sine function is even or odd.
Explanation
The sine function is odd.
Problem 3
A function is odd if \(f(-x) = -f(x)\). For sine, \(\sin(-x) = -\sin(x)\), which confirms that it is an odd function.
If \(\sin(x) = \frac{\sqrt{3}}{2}\), what is \(x\) in degrees?
Explanation
\(x = 60^\circ\).
Problem 4
The sine of \(60^\circ\) is \(\frac{\sqrt{3}}{2}\). Thus, \(x = 60^\circ\).
Using the Pythagorean identity, find \(\cos(x)\) if \(\sin(x) = 0.6\).
Explanation
\(\cos(x) = 0.8\).
The period of the cosine function is \(2\pi\).
1.Is the sine function even or odd?
2.What is the range of the sine function?
3.How do you use the Pythagorean identity?
4.How do you find the values of trigonometric functions at notable angles?
Common Mistakes and How to Avoid Them in Properties of Trigonometric Functions
Students often make mistakes when working with trigonometric functions due to misunderstandings of their properties.
Here are some common mistakes and how to avoid them.
Explore More trigonometry
Hiralee Lalitkumar Makwana
About the Author
Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.
Fun Fact
: She loves to read number jokes and games.
