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Inverse Trigonometric Functions Class 12 Maths Chapter 2 CBSE Notes - 2025-26

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Maths Notes for Chapter 2 Inverse Trigonometric Functions Class 12 - FREE PDF Download

Inverse Trigonometric Functions Class 12 Notes explore the basics of inverse trigonometric functions, which are important in solving complex maths problems. These revision notes cover the definitions, properties, and key operations related to these functions. Class 12 Maths Revision Notes help students understand how inverse trigonometric functions work and how they are applied in different situations.


Following the CBSE Class 12 Maths Syllabus, the notes explain important topics like principal values, domains, ranges, and different uses of inverse trigonometric functions. The notes are designed to make difficult topics easier to understand and to help students prepare well for exams. By using Inverse Trigonometry Class 12 Notes, students can grasp important concepts and feel more confident in their math skills.

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Access Class 12 Maths Chapter 2 Inverse Trigonometric Functions - PDF Download

Domain and Range of all Inverse Trigonometric Functions

Function

Domain

Range

1. y=sin1x if x=siny

1x1

[π2,π2]

2. y=cos1xif x=cosy

1x1

[0,π]

3. y=tan1xif x=tany

<x<

(π2,π2)

4. y=cot1xif x=coty

<x<

(0,π)

5.y=cosec1xif x=cosecy

(,1][1,)

[π2,0)(0,π2]

6. y=sec1xif x=secy

(,1][1,)

[0,π2)(π2,π]

  • We must note that inverse trigonometric functions cannot be expressed in terms of trigonometric functions as their reciprocals. For example, sin1x1sinx.

  • The principal value of a trigonometric function is that value which lies in the range of principal branch.

  • The functions sin1x & tan1x are increasing functions in their domain.

  • The functions cos1x & cot1x are decreasing functions in over domain.

 

Graphs of Inverse Trigonometric Functions

a) Graph of sin1x is shown below,


Graph of sin


b) Graph of cos1x is shown below,


Graph of cos


c) Graph of tan1x is shown below,


Graph of tan


d) Graph of cosec1x is shown below,


Graph of cos e


e) Graph of sec1x is shown below,


Graph of sec


f) Graph of cot1x is shown below,


Graph of cot


Properties of Inverse Trigonometric Functions

1. Property I

(a). sin1(1x)=cosec1x, for all x(,1][1,)

Let us prove this by considering cosec1x=θ ……(i)

Taking cosec on both sides,

x=cosecθ

Using reciprocal identity,

1x=sinθ

{x(,1][1,)}1x[1,1]{0}

cosec1x=θθ[π2,π2]{0}

θ=sin1(1x) ……(ii)

From (i) and (ii), we get

sin1(1x)=cosec1x

Hence proved.

b). cos1(1x)=sec1x, for all x(,1][1,)

Let us prove this by taking sec1x=θ   ……(i)

Taking sec on both sides,

x=secθ

Using reciprocal identity,

1x=cosθ

θ=cos1(1x) ……(ii)

Then, x(,1][1,) and θ[0,π]{π2}

{x=(,1][1,)1x[1,1]{0} and θ[0,π]

From (i) and (ii), we get

cos1(1x)=sec1(x)

Hence proved.

c. tan1(1x)={cot1x, for x>0π+cot1x, for x<0 

Let us prove this by taking cot1x=θ. Then xR,x0 and θ[0,π]   ……(i)

Now there are two cases that arise:

Case I: When x>0

In this case, we have θ(0,π2)

Considering cot1x=θ 

Taking cot on both sides,

x=cotθ

Using reciprocal property,                               

1x=tanθ

θ=tan1(1x)  ……(ii)

From (i) and (ii), we get   {θ(0,π2)}

tan1(1x)=cot1x, for all x>0

Case II: When x<0

In this case, we have θ(π2,π) {x=cotθ<0}

Now, π2<θ<π

π2<θπ<0

θπ(π2,0)

cot1x=θ

Taking cot on both sides,

x=cotθ

Using reciprocal property,

1x=tanθ

1x=tan(πθ)

1x=tan(θπ) {tan(πθ)=tanθ}

θπ=tan1(1x) {θπ(π2,0)}

tan1(1x)=π+θ   ……(iii)

From (i) and (iii), we get

tan1(1x)=π+cot1x, if x<0

Hence it is proved that tan1(1x)={cot1x, for x>0π+cot1x, for x<0.

 

2. Property II

  1. sin1(x)=sin1(x), for all x[1,1]

  2. tan1(x)=tan1x, for all xR

  3. cosec1(x)=cosec1x, for all x(,1][1,)

Clearly, x[1,1] for all x[1,1]

Let us prove a) by taking sin1(x)=θ

Then, taking sin on both sides, we get

x=sinθ   ……(i)

x=sinθ

x=sin(θ)

θ=sin1x

{x[1,1] and θ[π2,π2] for all θ[π2,π2]}

θ=sin1x  ……(ii)

From (i) and (ii), we get

sin1(x)=sin1(x)

Hence proved.

The b) and c) properties can also be proved in the similar manner.

3. Property III

  1. cos1(x)=πcos1(x), for all x[1,1]

  2. sec1(x)=πsec1x, for all x(,1][1,)

  3. cot1(x)=πcot1x, for all xR

Clearly, x[1,1] for all x[1,1]

Let us prove it by taking cos1(x)=θ  ……(i)

Then, taking cos on both sides, we get

x=cosθ

x=cosθ

x=cos(πθ)

{x[1,1] and πθ[0,π] for all θ[0,π]}

cos1x=πθ

θ=πcos1x ……(ii)

From (i) and (ii), we get

cos1(x)=πcos1(x)

Hence Proved.

The b) and c) properties can also be proved in the similar manner.

4.  Property IV

a) sin1x+cos1x=π2, for all x[1,1]

Let us prove it by taking sin1x=θ  ……(i)

Then, θ[π2,π2] [x[1,1]]

π2θπ2

π2θπ2

0π2θπ

π2θ[0,π]

Now we consider sin1x=θ

Taking sin on both sides, we get

x=sinθ

Changing functions, we get

x=cos(π2θ)

cos1x=π2θ

{x[1,1] and (π2θ)[0,π]}                                                

θ+cos1x=π2 ……(ii)

From (i) and (ii), we get

sin1x+cos1x=π2

Hence proved.

b) tan1x+cot1x=π2, for all xR

Let us prove it by taking tan1x=θ ……(i)

Then, θ(π2,π2) {xR}

π2<θ<π2

π2<θ<π2

0<π2θ<π

(π2θ)(0,π)

Now consider tan1x=θ

Taking tan on both sides, we get

x=tanθ

x=cot(π2θ)

cot1x=π2θ {π2θ(0,π)}

θ+cot1x=π2   ……(ii)

From (i) and (ii), we get

tan1x+cot1x=π2

c) sec1x+cosec1x=π2, for all x(,1][1,)

Let us prove it by taking sec1x=θ   ……(i)

Then, θ[0,π]{π2} {x(,1][1,)}

0θπ,θπ2

πθ0,θπ2

π2π2θπ2,π2θ0

(π2θ)[π2,π2],π2θ0

Now considering sec1x=θ

Taking sec on both sides, we get

x=secθ

x=cosec(π2θ)

cosec1x=π2θ

{(π2θ)[π2,π2],π2θ0}

θ+cosec1x=π2   ….…(ii)

From (i) and (ii), we get

sec1x+cosec1x=π2

 

5. Property V

  1. tan1x+tan1y=tan1x+y1xy,xy<1

  2. tan1xtan1y=tan1xy1+xy,xy>1

  3. tan1x+tan1y=π+tan1(x+y1xy),xy>1;x,y=0

Let us prove a) by taking tan1x=θ and tan1y=ϕ.

Taking tan on both sides for both terms, we get x=tanθ and y=tanϕ.

Using formula for tan(A+B)=tanA+tanB1tanAtanB, we can write

tan(θ+ϕ)=tanθ+tanϕ1tanθtanϕ

Writing in terms of x and y,

tan(θ+ϕ)=x+y1xy

θ+ϕ=tan1(x+y1xy)

Therefore tan1x+tan1y=tan1x+y1xy,xy<1.

Hence proved.

The properties b) and c) can be proved in similar manner by considering y as y and y as x respectively in the above proof.

 

6.  Property VI

  1. 2tan1x=sin12x1+x2,|x|1

  2. 2tan1x=cos11x21+x2,x0

  3. 2tan1x=tan12x1x2,1<x<1

Let us prove a) by taking tan1x=y.

Taking tan on both sides, we get

x=tany

We can write sin12x1+x2 as sin12tany1+tan2y.

Using formula sin2x=2tanx1+tan2x, we get

sin12x1+x2=sin1(sin2y)

Using sin1(sinx)=x, this can be written as

sin12x1+x2=2y

sin12x1+x2=2tan1x

Hence proved.

The same process can be followed to prove properties b) and c) as well.

 

7.  Property VII

  1. sin(sin1x)=x, for all x[1,1]

  2. cos(cos1x)=x, for all x[1,1]

  3. tan(tan1x)=x, for all xR

  4. cosec(cosec1x)=x, for all x(,1][1,)

  5. sec(sec1x)=x, for all x(,1][1,)

  6. cot(cot1x)=x, for all xR


Let us prove a). We know that, if f:AB is a bijection, then f1:BA exists such that fof1(y)=f(f1(y))=y for all yB.

Clearly, all these results are direct consequences of this property.

Aliter: Let θ[π2,π2] and x[1,1] such that sinθ=x.

Taking sin on both sides, θ=sin1x

x=sinθ=sin(sin1x)

Hence, sin(sin1x)=x for all x[1,1] and we proved it.

We can prove properties from b) to f) in a similar manner.

It should be noted that, sin1(sinθ)θ, if [π2,π2].

Let us understand this better. The function y=sin1(sinx) is periodic and has period 2π.

To draw this graph, we should draw the graph for one interval of length 2π and repeat the entire values of x.

As we know,

sin1(sinx)={x; π2xπ2(πx); π2πx<π2(i.e.,π2x3π2)

sin1(sinx)={x, π2xπ2πx, π2x3π2,

This is plotted as

This is plotted as


Thus, we can note that the graph for y=sin1(sinx) is a straight line up and a straight line down with slopes 1 and 1 respectively lying between [π2,π2].

The below result for the definition of sin1(sinx) must be kept in mind. y=sin1(sinx)={x+2π; 5π2x3π2πx; 3π2xπ2x; π2xπ2πx; π2x3π2x2π; 3π2x5π2 ...and so on

Now we consider y=cos1(cosx) which is periodic and has period 2π.

To draw this graph, we should draw the graph for one interval of length 2π and repeat the entire values of x of length 2π        

As we know,

cos1(cosx)={x; 0xπ2πx; 02πxπ, cos1(cosx)={x; 0xπ2πx; πx2π,

Thus, it has been defined for 0<x<2π that has length 2π.

So, its graph could be plotted as;

the curve


Thus, the curve y=cos1(cosx) and we can not the results as cos1(cosx)={x, if x[π,0]x, if x[0,π]2πx, if x[π,2π]2π+x, if x[2π,3π] and so on.

Next, we consider y=tan1(tanx) which is periodic and has period π.

To draw this graph, we should draw the graph for one interval of length π and repeat the entire values of x.

We know tan1(tanx)={x;π2<x<π2}. Thus, it has been defined for π2<x<π2 that has length π.

The graph is plotted as

the curve for


Thus, the curve for y=tan1(tanx), where y is not defined for x(2n+1)π2. The below result can be kept in mind.

tan1(tanx)={πx, if x[3π2,π2]x, if x[π2,π2]xπ, if x[π2,3π2]x2π, if x[3π2,5π2] and so on.

Additional Formulas

  1. sin1x+sin1y=sin1(x1y2+y1x2)

  2. sin1xsin1y=sin1(x1y2y1x2)

  3. cos1x+cos1y=cos1(xy1x21y2)

  4. cos1xcos1y=cos1(xy+1x21y2)

  5. tan1x+tan1y+tan1z=tan1[x+y+zxyz1xyyzzx], if x>0,y>0,z>0&xy+yz+zx<1

  6. tan1x+tan1y+tan1z=π when x+y+z=xyz

  7. tan1x+tan1y+tan1z=π2 when xy+yz+zx=1

  8. sin1x+sin1y+sin1z=3π2x=y=z=1

  9. cos1x+cos1y+cos1z=3π; x=y=z=1

  10. tan11+tan12+2tan13=tan11+tan112+tan113=π2


5 Important Formulas for Maths Class 12 Chapter 2 You Shouldn’t Miss!

S.No.

Important Formulas

1.

sin−1(x) Formula: sin(θ)=x and π2θπ2

2.

cos−1(x) Formula: cos1(x)=θ where cos(θ)=x and 0θπ

3.

tan⁡−1(x)\tan^{-1}(x)tan−1(x) Formula: tan1(x)=θ where tan(θ)=x and π2<θ<π2

4.

Addition Formula for sin⁡−1\sin^{-1}sin−1: sin1(x)+sin1(y)=sin1(x1y2+y1x2) if |x|,|y|1

5.

Addition Formula for cos⁡−1\cos^{-1}cos−1: cos1(x)+cos1(y)=πcos1(xy(1x2)(1y2)) if |x|,|y|1



Importance of Maths Chapter 2 Notes Inverse Trigonometric Functions Class 12

  • These notes simplify the understanding of inverse trigonometric functions, which are essential for solving complex maths problems.

  • They help students grasp the concept of principal value branches, which is important for accurate calculations.

  • The notes clarify the domain and range of inverse trigonometric functions, which is important for solving equations.

  • They enhance problem-solving skills by providing clear explanations and examples of how these functions are used in various mathematical contexts.

  • Inverse Trigonometric Functions Class 12 Notes PDF aligns with the CBSE Class 12 Maths syllabus, helping students prepare effectively and confidently for board exams.


Tips for Learning the Class 12 Science Chapter 2 Inverse Trigonometric Functions

  • Start by thoroughly understanding the basic concepts of trigonometric functions, as this foundation is crucial for grasping inverse trigonometric functions.

  • Focus on principal value branches, as they can be challenging; practice identifying them for different functions.

  • Ensure you understand the domain and range of each inverse trigonometric function by practising related problems.

  • Study the graphs of inverse trigonometric functions to grasp their behaviour and range.

  • Practice solving various problems involving inverse trigonometric functions to solidify your understanding and prepare for exams.


Conclusion

The Revision Notes for Class 12 Maths Chapter on Inverse Trigonometric Functions simplify complex ideas, making them easier to grasp. They clearly explain key concepts such as principal value branches, domain, range, and the properties of inverse trigonometric functions. Inverse Trigonometric Functions Class 12 Notes PDF include helpful summaries and practice problems to reinforce learning. This chapter demonstrates how inverse trigonometric functions work and how to solve related problems. Regularly reviewing these notes will help students master the topic and perform better in their Class 12 Maths exams.


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FAQs on Inverse Trigonometric Functions Class 12 Maths Chapter 2 CBSE Notes - 2025-26

1. How do revision notes for Inverse Trigonometric Functions Class 12 help students master key concepts quickly?

Revision notes provide succinct summaries of definitions, properties, and formulas related to inverse trigonometric functions. By organising the material into clear sections—such as domains, ranges, principal values, and graphs—these notes make it easier for students to review major concepts and reinforce understanding in less time, supporting effective last-minute revision aligned with CBSE 2025–26 requirements.

2. What is the recommended sequence for revising the chapter on Inverse Trigonometric Functions in Class 12 Maths?

Begin with the basics of trigonometric functions and their domains and ranges. Next, study the definition of inverse trigonometric functions and focus on the principal value branches. Move on to learn key properties, standard formulas, and related graphs. End by practising property-based and mixed-concept questions to consolidate understanding before the exam.

3. Why is understanding the principal value branch crucial in inverse trigonometric functions?

The principal value branch ensures that every inverse trigonometric function yields a single, well-defined output for a given input. This prevents ambiguity in answers by restricting possible solutions to a standardised interval, which is essential for scoring accuracy in CBSE board exams and for solving equations without error.

4. How do the properties of inverse trigonometric functions simplify complex problems during revision?

Properties such as odd/even behaviour, addition and subtraction formulas, and identities like sin–1(x) + cos–1(x) = π/2 allow students to convert complicated expressions into simpler forms. Using these properties can greatly reduce calculation steps and help tackle mixed-concept problems quickly, making revision more efficient and effective.

5. What are the standard domains and ranges students should memorise for each inverse trigonometric function?

  • sin–1x: domain [–1, 1], range [–π/2, π/2]
  • cos–1x: domain [–1, 1], range [0, π]
  • tan–1x: domain (–∞, ∞), range (–π/2, π/2)
  • cot–1x: domain (–∞, ∞), range (0, π)
  • sec–1x: domain (–∞, –1] ∪ [1, ∞), range [0, π] (except π/2)
  • cosec–1x: domain (–∞, –1] ∪ [1, ∞), range [–π/2, π/2] (except 0)
Memorising these pairs is fundamental for accurate revision and application in exams.

6. How do graphs of inverse trigonometric functions support better understanding during quick revision?

Graphs visually display the domain, range, monotonicity, and key turning points of each inverse function. By studying these, students can quickly identify where each function is increasing or decreasing, spot principal branches, and verify answers graphically—facilitating faster and more reliable solutions during exams.

7. What common pitfalls should students avoid when revising inverse trigonometric functions for CBSE exams?

Students often confuse domains and ranges, apply incorrect principal value intervals, or misuse addition/subtraction formulas. Avoid these mistakes by paying special attention to property lists in revision notes, double-checking ranges for each function, and practising worked examples provided in the notes to reinforce correct application.

8. How are the properties of inverse trigonometric functions interconnected with other chapters in Class 12 Maths?

Inverse trigonometric properties frequently appear in calculus chapters (integration and differentiation) and in solving equations involving multiple mathematical concepts. Strong grasp of these properties enables students to transition seamlessly between chapters and apply inverse trigonometric identities in broader mathematical contexts, enhancing problem-solving skills overall.

9. What revision techniques are most effective for memorising formulas and properties from the chapter?

  • Create summary sheets featuring all major formulas and properties
  • Practice derivations of key properties (e.g., even/odd function behaviours)
  • Solve varied examples based on each property
  • Group similar identities to spot patterns
  • Review summary charts before tests for quick recall
Using these techniques strengthens concept retention and boosts revision speed.

10. How do revision notes ensure full alignment with the latest CBSE 2025–26 Maths syllabus for Inverse Trigonometric Functions?

Revision notes follow the official CBSE topic order, covering compulsory properties, proofs, standard graphs, and applications stated in the syllabus. They emphasise recent exam trends, include higher-order problem types, and clearly mark sections based on areas the board highlights as important—ensuring students revise exactly what is required for exam success.

11. Why is the understanding of odd and even properties of inverse trigonometric functions essential during revision?

Recognising which inverse functions are odd or even helps in simplifying expressions such as sin–1(–x) = –sin–1(x) and tan–1(–x) = –tan–1x. This knowledge allows for quick identification of answer signs and reduces errors in competitive and board exams.

12. How can understanding the proofs and logical steps behind properties help beyond rote memorisation?

Grasping the logical reasoning behind each property gives deeper insight into why a property holds, supporting flexibility when tackling unfamiliar problems. It also boosts confidence in derivations, minimises mistakes due to rote errors, and prepares students for higher-order CBSE 2025–26 exam questions that test application instead of memorisation alone.

13. What role do summary charts and revision maps play in quick last-minute preparation for Inverse Trigonometric Functions?

Summary charts and revision maps bring together all formulas, domains, ranges, and key properties in one place for fast reference. This accelerates revision by minimising page-flipping and helps ensure no important concept is left out when preparing for the CBSE Class 12 Maths exam’s Inverse Trigonometric Functions chapter.

14. How can mastering inverse trigonometric function properties help in solving integrals and equations in calculus?

A solid command of inverse trigonometric identities allows students to transform complex integrals or equations into standard forms that are easier to integrate or solve. These properties often provide the necessary substitutions and simplifications for efficient calculation in calculus problems across the Class 12 syllabus.

15. What makes a revision note ‘effective’ for the Inverse Trigonometric Functions chapter in board exam prep?

An effective revision note is concise, clearly highlights key formulas and proofs, organises properties by function, offers illustrative graphs, and uses solved examples to connect concepts. It aligns fully with the latest CBSE 2025–26 syllabus and is designed for step-wise revision, making even the most challenging concepts accessible for board-level mastery.