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Trigonometric Functions appeared 43 times across 3 years — 5% of Mathematics. This question is from Trigonometric Equations and Solutions.

Year 2026 2025 2024 Total
Questions 15 18 10 43

Let A=xin(0,π)-(π)/(2): (2/π)| x|+ (2/π)| x|=2 and B=x≥0:√(x)(√(x)-4)-3|√(x)-2|+6=0. Then n(A B) is equal to:

Solution & Explanation

Related Formula

Logarithmic addition property: (a) + (b) = (ab). Double angle sine formula: 2 x x = 2x.

Step 1: Simplify Set A

Combine the logarithmic elements:

(2/π) (| x| · | x|) = 2 | x x| = ((2)/(π))² = (4)/(π²) |2 x x| = (8)/(π²) ⇒ | 2x| = (8)/(π²)

Since π² ≈ 9.87, (8)/(π²) ≈ 0.81, which is less than 1. Plotting | 2x| = (8)/(π²) over the specified range x in (0, π) yields exactly 4 real intersection points.

Trigonometric Equations graph for Q55 - JEE Main 2025 Evening
Trigonometric Equations graph for Q55 - JEE Main 2025 Evening

Hence, n(A) = 4.

Step 2: Simplify Set B

Let √(x) = t where t ≥ 0. The equation becomes:

t(t-4) - 3|t-2| + 6 = 0

Case I: If t < 2 :

t² - 4t - 3(-(t-2)) + 6 = 0 ⇒ t² - 4t + 3t - 6 + 6 = 0 ⇒ t² - t = 0 t = 0, 1 ⇒ x = 0, 1

Case II: If t > 2 :

t² - 4t - 3(t-2) + 6 = 0 ⇒ t² - 4t - 3t + 6 + 6 = 0 ⇒ t² - 7t + 12 = 0 (t-3)(t-4) = 0 ⇒ t = 3, 4 ⇒ x = 9, 16

Hence, set B = 0, 1, 9, 16, giving n(B) = 4.

Step 3: Calculate Union

Since all elements of set A are non-integral angles in (0, π) and elements of set B are pure integers, the sets are completely disjoint (A B =).

n(A B) = n(A) + n(B) = 4 + 4 = 8
Pattern Recognition

Always separate functions into disjoint numeric domains (e.g., angles vs. whole integers) to conclude unions without performing tedious tracking of individual values manually.

Chapter Mix

Class 11 Physics: Trigonometric Functions Class 11 Mathematics: Sets

Reference Study Guides

More Trigonometric Functions Previous-Year Questions — Page 5

Q68 jee_main_2025_08_april_evening Simplification of Trigonometric Expressions
The value of ⁻¹ ( 1 + ^ 2 (2) - 1 (2)) - ⁻¹ ( 1 + ^ 2 ((1)/(2)) + 1 ((1)/(2))) is equal to
  • A. π -(5)/(4)
  • B. π -(3)/(2)
  • C. π +(3)/(2)
  • D. π +(5)/(2)

Solution

Related Formula
√(1+ ²θ) = | θ|
Core Logic

Track angular positions across quadrants accurately. Evaluate positive/negative absolute value signs based on component radian locations before reducing formulas.

Step 1: Simplify First Exponent Operand

For tracking segment angle height θ = 2 radians (Quadrant II), cosine terms switch below zero:

| 2| = - 2 (- 2 - 1)/( 2) = (-1 - 2)/( 2) = - 1
Step 2: Simplify Second Exponent Operand

For tracking segment angle height θ = 1/2 radian (Quadrant I), expressions remain positive:

| (1/2)| = (1/2) ( (1/2) + 1)/( (1/2)) = (1 + (1/2))/( (1/2)) = (1/4)
Step 3: Combine Structural Terms

Apply inverse mapping functions carefully:

⁻¹(- 1) - ⁻¹( (1)/(4)) = (π - 1) - (1)/(4) = π - (5)/(4)
Pattern Recognition

Radian values like 2 sit over 90^° but beneath 180^°. Missing quadrant validation tags is a common trap in inverse identity tracking.

Chapter Mix

Class 12 Mathematics: Inverse Trigonometric Functions

Q52 jee_main_2025_29_jan_evening Trigonometric Identities
If x + ² x = 1, x in (0, (π)/(2)), then ( ¹² x + ¹² x) + 3 ( ¹⁰ x + ¹⁰ x + ⁸ x + ⁸ x) + ( ⁶ x + ⁶ x) is equal to
  • A. 4
  • B. 3
  • C. 2
  • D. 1

Solution

Related Formula

Fundamental identities:

² x + ² x = 1 x = ( x)/( x)

Algebraic identity for a perfect cube:

(A + B)³ = A³ + 3A²B + 3AB² + B³
Core Logic

Given equation:

x + ² x = 1 x = 1 - ² x = ² x

Dividing both sides by ² x:

( x)/( ² x) = 1 x x = 1 x = x
Step 1: Simplify the Expression

Since x = x, we can substitute x with x throughout the given expression:

( ¹² x + ¹² x) + 3( ¹⁰ x + ¹⁰ x + ⁸ x + ⁸ x) + ( ⁶ x + ⁶ x) = 2 ¹² x + 6 ¹⁰ x + 6 ⁸ x + 2 ⁶ x = 2[ ¹² x + 3 ¹⁰ x + 3 ⁸ x + ⁶ x]
Step 2: Apply the Cubic Identity

Notice that the expression inside the brackets matches the expansion of a perfect cube:

= 2[( ⁴ x + ² x)³]

Since ² x = x, it follows that ⁴ x = ² x. Substituting these back in:

= 2[( ² x + x)³]

We know from the problem statement that x + ² x = 1. Therefore:

= 2(1)³ = 2

Pattern Recognition

When given x + ² x = 1, the substitution ² x = x or x = x is a classic identity trick. Recognizing binomial coefficients (1, 3, 3, 1) immediately signals to condense into a full cube structure.

Chapter Mix

Class 11 Mathematics: Trigonometric Functions

Q jee_main_2025_28_jan_morning Sum of Inverse Trigonometric Functions
( ⁻¹(3)/(5) + ⁻¹(5)/(13) + ⁻¹(33)/(65)) is equal to:
  • A. 1
  • B. 0
  • C. (33)/(65)
  • D. (32)/(65)

Solution

Related Formula

Standard tangent identity sum format:

⁻¹ x + ⁻¹ y = ⁻¹ ((x+y)/(1-xy))
Core Logic

Convert all components into tangent mappings: ⁻¹(3)/(5) = ⁻¹(3)/(4) ⁻¹(5)/(13) = ⁻¹(5)/(12) ⁻¹(33)/(65) = ⁻¹(33)/(56)

Step 1: Evaluating the Mapped Component Sum

Summing the first two components:

⁻¹(3)/(4) + ⁻¹(5)/(12) = ⁻¹(((3)/(4) + (5)/(12))/(1 - (15)/(48))) = ⁻¹(56)/(33)
Step 2: Applying Cofunction Complements

Notice that ⁻¹(33)/(56) = ⁻¹(56)/(33). Combining everything inside the function:

( ⁻¹(56)/(33) + ⁻¹(56)/(33)) = ((π)/(2)) = 0
Pattern Recognition

Look for reciprocal fractional identities across matching inverse blocks—they easily merge using the ⁻¹ x + ⁻¹ x = (π)/(2) identity.

Chapter Mix

Class 12 Maths: Inverse Trigonometric Functions

Q60 jee_main_2025_03_april_morning Trigonometric Equations
The number of solutions of the equation 2x + 3 x = π, xin[-2π, 2π] - ±(π)/(2), ±(3π)/(2) is[cite: 612, 613]:
  • A. 6
  • B. 5
  • C. 4
  • D. 3

Solution

Related Formula

Intersection method for transcendental configurations: f(x) = g(x) Plot both curves separately to observe distinct intersection markers inside target domain spans.

Trigonometric Equations diagram for Q60 - JEE Main 2025 Morning
Trigonometric Equations diagram for Q60 - JEE Main 2025 Morning

Core Logic

Rearrange terms to group equations into known standard graphing profiles [cite: 1321]: 3 x = π - 2x x = (π)/(3) - (2x)/(3) [cite: 1321]

Plot the linear equation line y = (π)/(3) - (2x)/(3) along with multiple period tracks of the trigonometric function y = x within the interval [-2π, 2π][cite: 613, 1321].

Step 1: Point analysis across branches

The line has a negative slope and passes through (0, π/3) and (3π/2, 0). Looking across distinct interval chunks separated by asymptotes[cite: 613]:

  • Branch 1 (-2π, -(3π)/(2)): 1 intersection
  • Branch 2 (-(3π)/(2), -(π)/(2)): 1 intersection
  • Branch 3 (-(π)/(2), (π)/(2)): 1 intersection near origin
  • Branch 4 ((π)/(2), (3π)/(2)): 1 intersection
  • Branch 5 ((3π)/(2), 2π): 1 intersection
  • Counting all distinct points across valid domains gives 5 solutions total[cite: 1337].

Pattern Recognition

A linear curve intersecting tangent asymptote branches will cut exactly once through every continuous range slice unless the line is strictly horizontal or parallel to asymptotes.

Chapter Mix

Class 11 Mathematics: Trigonometric Functions

Q jee_main_2025_04_april_evening Summation of Series
The sum of the infinite series ⁻¹ ((7)/(4)) + ⁻¹ ((1 9)/(4)) + ⁻¹ ((3 9)/(4)) + ⁻¹ ((6 7)/(4)) + . is :-
  • A. (π)/(2) + ⁻¹((1)/(2))
  • B. (π)/(2) - ⁻¹((1)/(2))
  • C. (π)/(2) + ⁻¹((1)/(2))
  • D. (π)/(2) - ⁻¹((1)/(2))

Solution

Related Formula

The general transformation formula for a difference of tangents is:

⁻¹x - ⁻¹y = ⁻¹((x-y)/(1+xy))
Core Logic

Let the general term of the series be Tₙ. Examining the numerators (7, 19, 39, 67,):

The differences between consecutive terms are 12, 20, 28,, which forms an arithmetic progression with a common difference of 8.

Thus, the general term for the sequence in the numerator can be found using difference methods:

Numerator = 4n² + 3

Therefore, the n-th term Tₙ is:

Tₙ = ⁻¹((4n² + 3)/(4)) = ⁻¹((4)/(4n² + 3))
Step 1: Rewriting the general term for telescoping sum

Divide the numerator and denominator inside the argument by 4:

Tₙ = ⁻¹((1)/(n² + (3)/(4))) = ⁻¹((1)/(1 + (n² - (1)/(4))))

Factorize n² - (1)/(4) as a difference of squares:

Tₙ = ⁻¹(((n + (1)/(2)) - (n - (1)/(2)))/(1 + (n + (1)/(2))(n - (1)/(2))))

Using the difference formula for ⁻¹:

Tₙ = ⁻¹(n + (1)/(2)) - ⁻¹(n - (1)/(2))
Step 2: Telescoping summation

Expanding the sum up to n terms:

Sₙ = Σk=1ⁿ Tk = [ ⁻¹((3)/(2)) - ⁻¹((1)/(2))] + [ ⁻¹((5)/(2)) - ⁻¹((3)/(2))] + + [ ⁻¹(n + (1)/(2)) - ⁻¹(n - (1)/(2))]

All intermediate terms cancel out, leaving:

Sₙ = ⁻¹(n + (1)/(2)) - ⁻¹((1)/(2))
Step 3: Infinite limit evaluation

Taking the limit as n → ∞:

S_∞ = n → ∞ [ ⁻¹(n + (1)/(2)) - ⁻¹((1)/(2))] = (π)/(2) - ⁻¹((1)/(2))
Pattern Recognition

Whenever you see an infinite series involving ⁻¹ or ⁻¹, try to rearrange the denominator into the form 1 + xy and check if the numerator matches x - y to set up a standard telescoping structure.

Chapter Mix

Class 12 Mathematics: Inverse Trigonometric Functions Class 11 Mathematics: Sequences and Series

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