CUET UG Mathematics Booster Test 1 - Inverse Trigonometric Functions
📌 Answers are locked once submitted — results and explanations appear at the end.
QUESTION 1 OF 20
If f(x) is an invertible function with domain X and range Y, what are the domain and range of its inverse g?
QUESTION 2 OF 20
Match the inverse trigonometric function to its principal value branch range:
| List 1 | List 2 |
|---|---|
| 1. cos⁻¹ | a. (-π/2, π/2) |
| 2. cosec⁻¹ | b. (0, π) |
| 3. tan⁻¹ | c. [0, π] |
| 4. cot⁻¹ | d. [-π/2, π/2] - {0} |
QUESTION 3 OF 20
For the tangent function, which intervals represent restricted domains where the function becomes bijective?
I. (-π/2, π/2)
II. (π/2, 3π/2)
III. (-3π/2, -π/2)
QUESTION 4 OF 20
Which of the following statements is incorrect regarding the function y = sec⁻¹ x?
QUESTION 5 OF 20
In a calculus problem involving numerical substitution, the expression 3sin⁻¹(x) is modeled. According to the properties of inverse trigonometric functions, 3sin⁻¹(x) = sin⁻¹(3x - 4x³). At x = 1/2, calculate the numerical value of 3*sin⁻¹(x) in radians.
QUESTION 6 OF 20
An engineering plot requires finding the principal value of cot⁻¹(-1/√3). Which region of the graph will the angle lie in?
QUESTION 7 OF 20
Consider the dataset of the principal values:
a = sin⁻¹(1/2),
b = sin⁻¹(-1/2),
c = cos⁻¹(1/2).
Calculate the arithmetic mean (average) of these values.
QUESTION 8 OF 20
From the set of values {-1, -1/2, 0, 1/2, 1}, an input x is chosen at random. What is the theoretical probability that cos⁻¹(x) results in an angle greater than or equal to π/2?
QUESTION 9 OF 20
Vector v is defined as v = tan⁻¹(1) i + tan⁻¹(-1) j. What is the numerical sum of its components?
QUESTION 10 OF 20
The area of a triangle is given by A = (1/2) * base * height. If base = cot⁻¹(1) and height = 4/π, what is the area?
QUESTION 11 OF 20
An integral evaluates to the boundary expression y = sec⁻¹(2/√3). What is the exact value of y?
QUESTION 12 OF 20
Assertion (A): The principal value of cosec⁻¹(2) is π/6.
Reason (R): cosec(π/6) = 2 and π/6 lies in the interval [-π/2, π/2] - {0}.
QUESTION 13 OF 20
Arrange the following expressions in ascending order of their analytical values:
1. sin⁻¹(sin 3π/5)
2. cos⁻¹(cos 13π/6)
3. tan⁻¹(tan π/4)
4. sin⁻¹(-1/2)
QUESTION 14 OF 20
To find the principal value branch of sec⁻¹, the domain of the secant function is restricted to:
QUESTION 15 OF 20
If the natural range of the cosine function is [-1, 1], what is the principal value of cos⁻¹(-1/2)?
QUESTION 16 OF 20
The range of the inverse function y = tan⁻¹ x is:
QUESTION 17 OF 20
A function f: R → R defined by f(x) = sin x is not invertible because:
QUESTION 18 OF 20
Given tan⁻¹(√3) = y, what is the analytical value of y?
QUESTION 19 OF 20
QUESTION 20 OF 20
Test Complete!
Answer Review
1 If f(x) is an invertible function with domain X and range Y, what are the domain and range of its inverse g?
Inverse swaps inputs and outputs. Domain of inverse equals original range. Range of inverse equals original domain.
For an invertible function f: X → Y, the inverse function reverses mappings. Hence the domain of g=f⁻¹ becomes Y and the range becomes X. Option B correctly states this interchange. Options A, C, and D ignore the reversal property fundamental to inverse functions.
- Option A → Keeps domain and range unchanged, which is incorrect for inverses.
- Option C → Both domain and range cannot simultaneously equal Y.
- Option D → Both domain and range cannot simultaneously equal X.
Used: Contextual/Tonal Matching
Application:
- Recall that inverse functions reverse the original mapping direction.
Final Logic:
- Inverse functions interchange domain and range.
"Inverse flips domain and range."
2 Match the inverse trigonometric function to its principal value branch range:
| List 1 | List 2 |
|---|---|
| 1. cos⁻¹ | a. (-π/2, π/2) |
| 2. cosec⁻¹ | b. (0, π) |
| 3. tan⁻¹ | c. [0, π] |
| 4. cot⁻¹ | d. [-π/2, π/2] - {0} |
cos⁻¹ range is [0,π]. tan⁻¹ range is (-π/2,π/2). cot⁻¹ range is (0,π).
The standard principal ranges are: cos⁻¹x → [0,π], cosec⁻¹x → [-π/2,π/2]−{0}, tan⁻¹x → (-π/2,π/2), cot⁻¹x → (0,π). Thus the correct matching is 1-c, 2-d, 3-a, 4-b, making option C correct.
- Option A → Incorrectly assigns cosec⁻¹ and cot⁻¹ ranges.
- Option B → Misplaces cos⁻¹ and tan⁻¹ ranges.
- Option D → cos⁻¹ does not have range excluding zero.
Used: Option Grouping
Application:
- Match each inverse trigonometric function with its standard NCERT principal branch.
Final Logic:
- Correct range identification gives the exact matching.
"Cos: [0,π], Tan: open ±π/2."
3 For the tangent function, which intervals represent restricted domains where the function becomes bijective?
I. (-π/2, π/2)
II. (π/2, 3π/2)
III. (-3π/2, -π/2)
Tangent is monotonic between asymptotes. Each interval avoids discontinuities. Hence tangent becomes bijective there.
The tangent function is continuous and strictly increasing between consecutive vertical asymptotes. Therefore intervals like (-π/2,π/2), (π/2,3π/2), and (-3π/2,-π/2) all make tangent bijective. Hence statements I, II, and III are correct, making option D the correct answer.
- Option A → Ignores other valid bijective intervals.
- Option B → Excludes interval III unnecessarily.
- Option C → Omits the standard principal branch interval.
Used: Elimination
Application:
- Check whether tangent remains one-one and onto in each interval.
Final Logic:
- Every interval between consecutive asymptotes gives bijection.
"Between asymptotes, tan behaves perfectly."
4 Which of the following statements is incorrect regarding the function y = sec⁻¹ x?
sec⁻¹x exists for |x|≥1. Values between -1 and 1 are invalid. Hence option A is false.
The inverse secant function is defined only for x≤-1 or x≥1. Therefore its domain is (-∞,-1]∪[1,∞), not [-1,1]. Option B correctly gives the principal branch. Option C correctly describes inverse secant. Option D is also true because secant never lies strictly between -1 and 1.
- Option B → Correct principal branch for sec⁻¹x.
- Option C → Correct interpretation of inverse secant.
- Option D → True because secant values satisfy |sec x|≥1.
Used: Extreme Word Filter
Application:
- Check whether the stated interval fully satisfies secant output restrictions.
Final Logic:
- sec⁻¹x cannot accept values inside (-1,1).
"Sec inverse starts outside ±1."
5 In a calculus problem involving numerical substitution, the expression 3sin⁻¹(x) is modeled. According to the properties of inverse trigonometric functions, 3sin⁻¹(x) = sin⁻¹(3x - 4x³). At x = 1/2, calculate the numerical value of 3*sin⁻¹(x) in radians.
sin⁻¹(1/2)=π/6 Multiply by 3. Result becomes π/2.
At x=1/2, sin⁻¹(1/2)=π/6 because sine of π/6 equals 1/2. Therefore: 3sin⁻¹(1/2)=3×π/6=π/2. Thus option B is correct. Option A gives only the inverse sine value before multiplication. Options C and D produce incorrect multiples.
- Option A → Represents only sin⁻¹(1/2), not three times it.
- Option C → Incorrect multiplication of π/6.
- Option D → Exceeds the required calculated value.
Used: Substitution
Application:
- Insert x=1/2 directly into the expression and simplify.
Final Logic:
- Three times π/6 equals π/2.
"Half gives π/6; triple gives π/2."
6 An engineering plot requires finding the principal value of cot⁻¹(-1/√3). Which region of the graph will the angle lie in?
cot⁻¹ range is (0,π). Negative cotangent occurs in second quadrant. Hence angle lies in quadrant II.
The principal value range of cot⁻¹x is (0,π). Cotangent is negative in the second quadrant. Since cot(2π/3)=-1/√3, the required angle lies in the second quadrant. Therefore option C is correct. Other quadrants either produce positive cotangent or lie outside the principal range.
- Option A → Cotangent is positive in first quadrant.
- Option B → Fourth quadrant is not within cot⁻¹ principal range.
- Option D → Third quadrant also lies outside the principal branch interval.
Used: Contextual/Tonal Matching
Application:
- Use sign conventions of cotangent together with principal branch intervals.
Final Logic:
- Negative cotangent within (0,π) belongs to quadrant II.
"cot⁻¹ lives in (0,π)."
7 Consider the dataset of the principal values:
a = sin⁻¹(1/2),
b = sin⁻¹(-1/2),
c = cos⁻¹(1/2).
Calculate the arithmetic mean (average) of these values.
Values are π/6, -π/6, π/3. Sum equals π/3. Divide by 3 to get π/9.
The principal values are: sin⁻¹(1/2)=π/6, sin⁻¹(-1/2)=-π/6, cos⁻¹(1/2)=π/3. Their sum is π/3. Dividing by 3 gives π/9. Therefore option D is correct. The other options result from incorrect addition or averaging of the standard angles.
- Option A → Ignores cancellation between positive and negative terms.
- Option B → Incorrect averaging after summation.
- Option C → Represents only one of the individual values.
Used: Substitution
Application:
- Replace inverse trigonometric expressions with standard principal values.
Final Logic:
- Average equals (π/3)/3 = π/9.
"π/6 and -π/6 cancel."
8 From the set of values {-1, -1/2, 0, 1/2, 1}, an input x is chosen at random. What is the theoretical probability that cos⁻¹(x) results in an angle greater than or equal to π/2?
cos⁻¹x ≥ π/2 when x≤0. Valid values: -1, -1/2, 0. Probability = 3/5.
The cosine inverse function decreases from 0 to π as x increases from 1 to -1. Therefore cos⁻¹(x)≥π/2 whenever x≤0. From the given set, the valid values are -1, -1/2, and 0. Hence probability = 3/5, making option A correct.
- Option B → Counts only two valid values instead of three.
- Option C → Includes one positive value incorrectly.
- Option D → Greatly undercounts satisfying outcomes.
Used: Elimination
Application:
- Identify which x-values produce angles at least π/2.
Final Logic:
- Three out of five numbers satisfy x≤0.
"Cos inverse ≥90° means x nonpositive."
9 Vector v is defined as v = tan⁻¹(1) i + tan⁻¹(-1) j. What is the numerical sum of its components?
tan⁻¹(1)=π/4 tan⁻¹(-1)=-π/4 Sum equals zero.
The principal values are tan⁻¹(1)=π/4 and tan⁻¹(-1)=-π/4. Adding them gives: π/4 + (-π/4)=0. Hence option B is correct. Options A, C, and D result from incorrect handling of signs or principal values.
- Option A → Represents only positive contribution doubled.
- Option C → Far exceeds the actual sum.
- Option D → Incorrectly ignores the positive component.
Used: Substitution
Application:
- Replace inverse tangent terms using standard principal values.
Final Logic:
- Equal positive and negative values cancel completely.
"π/4 and -π/4 balance."
10 The area of a triangle is given by A = (1/2) * base * height. If base = cot⁻¹(1) and height = 4/π, what is the area?
cot⁻¹(1)=π/4 Use triangle area formula. Result simplifies to 1/2.
The principal value cot⁻¹(1)=π/4. Therefore: Area = (1/2)×(π/4)×(4/π). The π and 4 cancel, leaving: Area = 1/2. Thus option C is correct. The remaining options arise from incomplete simplification or formula misuse.
- Option A → Ignores the factor 1/2 in the area formula.
- Option B → Incorrect simplification involving π terms.
- Option D → Represents only the base value.
Used: Substitution
Application:
- Substitute cot⁻¹(1)=π/4 into the area formula directly.
Final Logic:
- Cancellation simplifies the area exactly to 1/2.
"π cancels completely."
11 An integral evaluates to the boundary expression y = sec⁻¹(2/√3). What is the exact value of y?
sec y = 2/√3 Therefore cos y = √3/2 Principal angle is π/6
Given sec⁻¹(2/√3)=y, we write sec y=2/√3. Taking reciprocal gives cos y=√3/2. The principal angle satisfying this is π/6. Hence option D is correct. Option A gives cosine 1/2, option B gives √2/2, and option C gives cosine zero, where secant is undefined.
- Option A → sec(π/3)=2, not 2/√3.
- Option B → sec(π/4)=√2, which does not match.
- Option C → secant is undefined at π/2 because cos(π/2)=0.
Used: Substitution
Application:
- Convert secant inverse into cosine form using reciprocal identities.
Final Logic:
- cos y=√3/2 corresponds to y=π/6.
"√3/2 means 30°."
12 Assertion (A): The principal value of cosec⁻¹(2) is π/6.
Reason (R): cosec(π/6) = 2 and π/6 lies in the interval [-π/2, π/2] - {0}.
cosec(π/6)=2 π/6 belongs to principal branch Hence assertion and reason are true
The inverse cosecant function uses the principal branch [-π/2,π/2]−{0}. Since cosec(π/6)=2 and π/6 lies in the principal interval, cosec⁻¹(2)=π/6. Therefore both Assertion and Reason are true, and the Reason correctly explains the Assertion. Hence option A is correct.
- Option B → Reason is mathematically correct.
- Option C → Assertion is true because cosec(π/6)=2.
- Option D → Both statements are valid according to principal value definitions.
Used: Contextual/Tonal Matching
Application:
- Verify both the trigonometric identity and principal branch condition together.
Final Logic:
- The reason directly justifies the assertion.
"cosec 30° = 2."
13 Arrange the following expressions in ascending order of their analytical values:
1. sin⁻¹(sin 3π/5)
2. cos⁻¹(cos 13π/6)
3. tan⁻¹(tan π/4)
4. sin⁻¹(-1/2)
sin⁻¹(-1/2)=-π/6 cos⁻¹(cos13π/6)=π/6 tan⁻¹(tanπ/4)=π/4 and sin⁻¹(sin3π/5)=2π/5
Evaluate each expression: 1 → sin⁻¹(sin3π/5)=2π/5 2 → cos⁻¹(cos13π/6)=π/6 3 → tan⁻¹(tanπ/4)=π/4 4 → sin⁻¹(-1/2)=-π/6 Ascending order: -π/6 < π/6 < π/4 < 2π/5. Thus the order is 4,2,3,1, making option C correct.
- Option A → Places the largest value first incorrectly.
- Option B → Does not begin with the negative value.
- Option D → Places 2π/5 before π/4 incorrectly.
Used: Substitution
Application:
- Reduce each inverse trigonometric expression to its principal value.
Final Logic:
- Numerical comparison gives order 4,2,3,1.
"Negative first, then small positives."
14 To find the principal value branch of sec⁻¹, the domain of the secant function is restricted to:
sec x undefined at π/2 Principal branch avoids repetition Hence interval excludes π/2
The secant function becomes bijective on the interval [0,π] excluding π/2, where secant is undefined. This restriction defines the principal branch for sec⁻¹x. Option A incorrectly includes π/2. Options B and C correspond to tangent or cosecant-related intervals rather than secant inverse.
- Option A → Includes π/2 where secant is undefined.
- Option B → Not the standard branch for secant inverse.
- Option C → Corresponds more closely to cosecant inverse ranges.
Used: Elimination
Application:
- Remove intervals containing undefined secant values or repeated outputs.
Final Logic:
- Only [0,π]−{π/2} gives bijection for secant.
"Sec inverse skips π/2."
15 If the natural range of the cosine function is [-1, 1], what is the principal value of cos⁻¹(-1/2)?
cos(2π/3)=-1/2 Principal range is [0,π] Hence principal value is 2π/3
The inverse cosine function has principal range [0,π]. Since cos(2π/3)=-1/2, the principal value of cos⁻¹(-1/2) is 2π/3. Option B gives cosine +1/2. Option C lies outside the principal range. Option D gives cosine -√3/2, not -1/2.
- Option B → cos(π/3)=1/2, not negative.
- Option C → Negative angle not allowed in cosine inverse principal branch.
- Option D → cos(5π/6)=-√3/2, not -1/2.
Used: Substitution
Application:
- Check standard cosine values within the principal interval [0,π].
Final Logic:
- Only 2π/3 gives cosine equal to -1/2.
"Cos inverse stays positive."
16 The range of the inverse function y = tan⁻¹ x is:
tan x undefined at ±π/2 Endpoints excluded from range Principal branch is open interval
The inverse tangent function has principal value range (-π/2,π/2). The endpoints are excluded because tangent is undefined there. Hence option B is correct. Option A incorrectly includes undefined endpoints. Options C and D correspond to cotangent-related intervals rather than tangent inverse.
- Option A → Includes ±π/2 where tangent is undefined.
- Option C → Represents cot⁻¹ principal range.
- Option D → Incorrect closed interval unrelated to tan⁻¹.
Used: Elimination
Application:
- Exclude angles where tangent function becomes undefined.
Final Logic:
- tan⁻¹x always lies strictly between ±π/2.
"Tan inverse never touches ±90°."
17 A function f: R → R defined by f(x) = sin x is not invertible because:
Sine repeats values periodically. Range limited to [-1,1]. Hence neither injective nor surjective on R→R.
The sine function repeats values, so it is not one-one. Its range is only [-1,1], not all real numbers, so it is not onto for codomain R. Therefore f:R→R is neither injective nor surjective. Hence option C is correct. Option D is false because sine is defined everywhere.
- Option A → Sine is not one-one because of periodicity.
- Option B → Sine is not onto when codomain is R.
- Option D → sin0=0, so the function is perfectly defined at zero.
Used: Elimination
Application:
- Check both injective and surjective conditions independently.
Final Logic:
- Failure of both conditions prevents invertibility.
"Sine repeats and stays bounded."
18 Given tan⁻¹(√3) = y, what is the analytical value of y?
tan(π/3)=√3 π/3 lies in principal range Hence inverse value is π/3
The principal range of tan⁻¹x is (-π/2,π/2). Since tan(π/3)=√3 and π/3 belongs to the principal interval, tan⁻¹(√3)=π/3. Therefore option D is correct. The remaining options produce tangent values 1/√3, 1, and undefined respectively.
- Option A → tan(π/6)=1/√3, not √3.
- Option B → tan(π/4)=1.
- Option C → tangent is undefined at π/2.
Used: Substitution
Application:
- Recall standard tangent values from trigonometric tables.
Final Logic:
- Only π/3 gives tangent equal to √3.
"√3 belongs to 60°."
19
tan⁻¹ uses a standard branch. Principal range is (-π/2,π/2). This branch defines uniqueness.
The inverse tangent function is conventionally defined using the range (-π/2,π/2), called the principal value branch. This interval ensures tangent remains one-one and onto. Therefore option A is correct. The other options are not standard NCERT terminology for inverse tangent definitions.
- Option B → Domain restriction applies to tangent, not the inverse range naming.
- Option C → Natural range refers to tangent outputs, not inverse branches.
- Option D → Asymptotic branch is not a standard mathematical term here.
Used: Contextual/Tonal Matching
Application:
- Use the exact terminology associated with inverse trigonometric branches.
Final Logic:
- (-π/2,π/2) is the standard principal branch for tan⁻¹.
"Tan inverse lives between ±90°."
20
Tangent range is all real numbers. Inverse domain equals original range. Hence tan⁻¹ domain is R.
The tangent function has range R on its restricted principal interval. Since the domain of an inverse equals the range of the original function, tan⁻¹x has domain R. Therefore option B is correct. Option A is the principal range of tan⁻¹, not its domain.
- Option A → Represents range of tan⁻¹, not its domain.
- Option C → Domain restriction [-1,1] applies to sine and cosine inverses.
- Option D → tan⁻¹ accepts every real number without exclusion.
Used: Contextual/Tonal Matching
Application:
- Relate inverse domain directly to tangent function range.
Final Logic:
- Since tan x covers all real numbers, tan⁻¹ accepts all real numbers.
"Tan inverse takes every real input."
