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JEE Main 2026 Preparation: Question Papers, Solutions, Mock Tests & Strategy Unacademy » JEE Study Material » Mathematics » Trigonometric identities and equation

Trigonometric identities and equation

Trigonometric identities are used to depict triangles with right angles. This study material discusses more on trigonometric identities.

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It is very useful to know trigonometric identities in right-angle triangles because you can figure out its sides and angles in a matter of minutes with just a few equations, which is very quick. Because of this, these identities are important in real-life situations, such as figuring out how tall a structure is, among other things. In this part, we’ll learn more about a lot of different types of identities.

Each side of a right angled triangle has a name:

What are trigonometric identities?

When generating a triangle identity equation, each potential value of the variable in the application domain is considered. Simply put, identity is a formula in which the variables included hold true for all possible values.

There are six distinct trigonometric identities in Trigonometric identities to be determined, instead of just one for algebraic identities such as sine, cosine, tangent, and secant. 

Formulas for Trigonometric identities

Trigonometric identities are equations that include Trigonometric functions in their design. These identities are valid for all possible variable combinations. For example, the Trigonometric Ratio is a mathematical ratio that defines the relationship between a right triangle’s angles and side lengths.

Sum and Difference – Trigonometric Identities

The sum and difference identities include the formulas of sin(A+B), cos(A-B), cot(A+B), etc.

  • sin (A+B) = sin A cos B + cos A sin B
  • sin (A-B) = sin A cos B – cos A sin B
  • cos (A+B) = cos A cos B – sin A sin B
  • cos (A-B) = cos A cos B + sin A sin B
  • tan (A+B) = (tan A + tan B)/(1 – tan A tan B)
  • tan (A-B) = (tan A – tan B)/(1 + tan A tan B)

Important Points to Remember About Reciprocal Identities, Periodicity Identities and Co-function Identities

  • Although the trigonometric ratios of additional angles are written, the trigonometric ratio itself does not change. Because only sin and cosec are positive in the second quadrant, where the angle is of the form (180-), this may be used to determine the sign of the equation.
  • The half-angle formula of tan is produced by first using the identity tan = sin/cos and then utilizing the half-angle formulae of sin and cos to get the half-angle formula of tan.
  • Trigonometric identities were obtained from Pythagorean trigonometry.
  • Pythagoras’ theorem defines the Pythagorean trigonometric identities in trigonometry.  

Application of Trigonometric Identities and Equations 

In spite of the fact that trigonometry has no direct practical applications, it is often employed in activities we find enjoyable. Sound travels like waves, and this pattern is important in the development of computer music, even if it isn’t exactly like a sine or cosine function. Computers break it down into individual sound waves to represent music mathematically. There are several fundamental trigonometric concepts that sound engineers need to grasp. Trigonometry is responsible for much of the soothing, stress-relieving effects of the music these sound engineers create.

Is it possible to measure the height of a structure or mountain using trigonometry?

A building’s height may be determined by its distance from the observer and its angle of elevation. Similar to the example before, if you know the value of one side and the corresponding angle, you can easily calculate the other side in the triangle.

Video Games and Trigonometry

When you see him effortlessly navigate the obstacles on the path. There is some curvature or parabolicity to his journey that allows him to overcome the hurdles in his way, rather than just jumping straight down the Y-axis. This is when Mario’s trigonometry skills come in handy. Trigonometry is of equal significance to these professionals since, as you know, the gaming business is all about IT and computers.

Flight engineering uses of Trigonometry

All of these factors must be considered by flight engineers when planning a flight. Wind plays an essential part in determining how and when an aircraft will get wherever required. This problem is answered by utilizing vectors to form a triangle and then solving it using trigonometry.” For example, consider an aircraft traveling at 234 mph, positioned 45 degrees north of east, with a southerly wind gusting to 20 mph. As a result of using trigonometry, you will find the third side of your triangle, which will assist you in steering the plane in a certain direction.

Physicists use Trigonometry

It is used to calculate the components of vectors, describe wave mechanics (both physical and electromagnetic), sum field strength and apply dot/cross products in trigonometry in physics. Trigonometry is used extensively in projectile motion.

Navigational Trigonometry

It explains how to use a compass to get to a straight line by using trigonometry to establish directions like north, south, east, and west. Use it to locate a certain spot in order to avoid getting lost. Using this method, you can figure out how far away a spot on the seafloor is from the coast. The ho

Conclusion: Reciprocal Identities

Apart from dominating the domain of algebra, as we’ve seen, identities also have a stronghold in geometry, as seen above. With the use of trigonometric identities, you can quickly determine the sides and angles of a right-angle triangle. Furthermore, these identities may be used in real-world scenarios, such as calculating the heights of structures we’ve just figured out. 

faq

Frequently asked questions

Get answers to the most common queries related to the IIT JEE Examination Preparation.

What exactly are the fundamental trigonometric ratios?

Ans : Sine, cosine, tangent are mathematical functions.

For trigonometry ratios, what are the formulae to use?

Ans : Sin A is the perpendicular/hypotenuse of the sine function. ...Read full

What are the three most important trigonometric functions?

Ans : The trigonometric functions Sin, Cos, and Tan are the most important ones.

How do you find the three Pythagorean identities?

Ans : The Pythagorean identities are derived from the Pythagorean theorem and establish the relatio...Read full

What purpose do Pythagorean identities serve, and why are they necessary?

Ans : As with any other identity, the Pythagorean identity may be utilized to rephrase trigonometri...Read full

Ans : Sine, cosine, tangent are mathematical functions.

Ans : Sin A is the perpendicular/hypotenuse of the sine function.

Cos A = Base/Hypotenuse is a mathematical expression.

Tan A is the perpendicular/base of the triangle.

Ans : The trigonometric functions Sin, Cos, and Tan are the most important ones.

Ans : The Pythagorean identities are derived from the Pythagorean theorem and establish the relationship between sine and cosine on the unit circle.

 

Ans : As with any other identity, the Pythagorean identity may be utilized to rephrase trigonometric formulae in more convenient but equivalent forms.

 

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