Physics Wallah

Secant Square x Formula, Derivation, Solved Examples

Secant Square x Formula: The Secant Square x Formula states: sec^2x = 1 + tan^2x, directly relating the square of secant to the square of tangent in trigonometry.
authorImageManoj Kumar3 Nov, 2023
Share

Share

Secant Square x Formula

Secant Square x Formula: Trigonometric functions describe the relationship between angles and sides. There are six main trigonometric functions: sine, cosine, tangent, cotangent, cosecant, and secant. These functions provide various values for different angles such as 30°, 60°, and more. Among these functions, sine, cosine, and tangent are the fundamental ones for classifying trigonometric functions.

Secant Square x Formula(sec 2 x):

sec 2 x=1+tan 2 x

Secant Square x Formula

Derivation of the Secant Square x Formula

In trigonometry, the functions sec θ and tan θ represent the secant and tangent functions, respectively. According to the Pythagorean identity for these functions, they can be expressed as: Sec 2 θ−Tan 2 θ=1 This equation can be rearranged to solve for Secant squared:

Sec 2 θ=1+Tan 2 θ

This derivation confirms that the secant squared x formula equals the sum of one and the tangent squared x function. Another approach to derive the Secant Square x Formula involves the identity related to the sum of squares of sine and cosine ratios: We start with the identity:

sin 2 x+cos 2 x=1

Dividing both sides by cos 2 x:

( sin 2 x/cos 2 x  ​ )+( cos 2 x/ cos 2 x  ​ )= 1 / cos 2 x​

This simplifies to: tan 2 x+1=sec 2 x Hence, it leads to the conclusion that the Secant Square x Formula is

sec 2 x=1+tan 2 x.

Secant Square x Formula Solved Examples

Example 1: Given:  tanx=  3/5 ​

Solution: Secant Square x Formula Sec 2 x=1+tan 2 x = 1 + ( 3/ 5 ) 2 =1+(  3/5 ​ ) 2 = 1 + 9 /25 =1+  9/25 ​ = (25 + 9) /25 = 34 /25 Therefore, Sec 2 x= 34 /25​

Example 2: Given: tanx= 4/5 ​

Solution: Secant Square x Formula Sec 2 x=1+tan 2 x = 1 + ( 4 /5 ) 2 =1+( 4/5 ​ ) 2 = 1 + 16 /25 =1+ 16 / 25 ​ = 41 /25 ​ Therefore, Sec 2 x= 41 ​/25

Example 3: Simplify (1+tan 2 A)(1−sinA)(1+sinA)

Solution: (1+tan 2 A)(1−sinA)(1+sinA) =(1+tan 2 A)(1−sin 2 A) = sec 2 A⋅cos 2 A =( 1/ cos 2 A  ​ )⋅cos 2 A = 1

Example 4: Determine the value of sec 2 x when tanx=  2/5 ​ .

Solution: Given tanx=  2/5 ​ . Using the Secant Square  x Formula: sec 2 x=1+tan 2 x = 1 + ( 2/ 5 ) 2 =1+(  2/5 ​ ) 2 = 1 + 4 /25 = = (25 + 4) / 25 = 29/ 25 Hence, sec 2 x equals  29/25 ​ when tanx is given as 2/5 ​ .

Example 5: Find the value of sec 2 x if cotx= 2/5 ​ .

Solution: Given that cotx= 2/5 ​ . Thus, tanx= 1/ cotx  ​ = 5/2 ​ . Now, applying the Secant Square x Formula: sec 2 x=1+tan 2 x = 1 + ( 5/2 ) 2 =1+( 5/2 ​ ) 2 = 1 + 25/4 = 29 /4 = 29/4 ​ Therefore, when cotx=  2/5 ​ , the value of sec 2 x is 29/ 4 .

Example 6: Determine the value of sec 2 x when tanx=  1/5 ​ .

Solution: Given tanx=  1/5 ​ . Using the Secant Square  x Formula: sec 2 x=1+tan 2 x = 1 + ( 1/ 5 ) 2 =1+(  1/5 ​ ) 2 = 1 + 1 /25 = = (25 + 1) / 25 = 26/ 25 Hence, sec 2 x equals  26/25 ​ when tan ⁡  tanx is given as 1/5 ​ .

Solved examples demonstrate the practical application of this formula to find secant squared values for given tangent of cotangent ratios. Mastering this formula allows for quick calculations and deeper comprehension of trigonometric relationships in various problem-solving scenarios.

Secant Square x Formula and its derivations is pivotal in trigonometry, offering insights into the relationship between secant and tangent functions. The formula sec2x = 1 + tan2x is derived through Pythagorean identities and relationships among sine, cosine, secant, and tangent functions.

Explore Now Online Course of Class 9 Neev Fastrack 2024 and Class 10 Udaan Fastrack 2024 to enhance your Maths knowledge. and build a strong foundation.

Related Links
Surface Area of a Prism Formula T-Test Formula
Trajectory Formula U Substitution Formula

Secant Square x Formula FAQs

What is the Secant Square x Formula?

The Secant Square x Formula states that secant squared (sec^2x) of an angle x is equal to 1 plus the square of the tangent (tan^2x) of the same angle.

How is the Secant Square x Formula derived?

It can be derived using Pythagorean identities for trigonometric functions, particularly involving secant and tangent, or through relationships between sine, cosine, and tangent functions.

Why is the Secant Square x Formula significant?

The formula is essential in trigonometry as it directly relates secant to the tangent function, allowing for quick calculations involving these trigonometric ratios.

How can the Secant Square x Formula be applied in problem-solving?

The formula is used to find the value of secant squared when the tangent of an angle is given, or vice versa, simplifying trigonometric expressions and identities.
Join 15 Million students on the app today!
Point IconLive & recorded classes available at ease
Point IconDashboard for progress tracking
Point IconMillions of practice questions at your fingertips
Download ButtonDownload Button
Banner Image
Banner Image
Free Learning Resources
Know about Physics Wallah
Physics Wallah is an Indian edtech platform that provides accessible & comprehensive learning experiences to students from Class 6th to postgraduate level. We also provide extensive NCERT solutions, sample paper, NEET, JEE Mains, BITSAT previous year papers & more such resources to students. Physics Wallah also caters to over 3.5 million registered students and over 78 lakh+ Youtube subscribers with 4.8 rating on its app.
We Stand Out because
We provide students with intensive courses with India’s qualified & experienced faculties & mentors. PW strives to make the learning experience comprehensive and accessible for students of all sections of society. We believe in empowering every single student who couldn't dream of a good career in engineering and medical field earlier.
Our Key Focus Areas
Physics Wallah's main focus is to make the learning experience as economical as possible for all students. With our affordable courses like Lakshya, Udaan and Arjuna and many others, we have been able to provide a platform for lakhs of aspirants. From providing Chemistry, Maths, Physics formula to giving e-books of eminent authors like RD Sharma, RS Aggarwal and Lakhmir Singh, PW focuses on every single student's need for preparation.
What Makes Us Different
Physics Wallah strives to develop a comprehensive pedagogical structure for students, where they get a state-of-the-art learning experience with study material and resources. Apart from catering students preparing for JEE Mains and NEET, PW also provides study material for each state board like Uttar Pradesh, Bihar, and others

Copyright © 2025 Physicswallah Limited All rights reserved.