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Trigonometric Functions appeared 27 times across 3 years — 3.1% of Mathematics. This question is from Trigonometric Identities.

Year 2026 2025 2024 Total
Questions 10 10 7 27

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

Solution & Explanation

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

Reference Study Guides

More Trigonometric Functions Previous-Year Questions — Page 4

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

Q70 jee_main_2025_04_april_morning Trigonometric Identities
If 10 ⁴θ + 15 ⁴θ = 6, then the value of (27 ⁶θ + 8 ⁶θ)/(16 ⁸θ) is:
  • A. (2)/(5)
  • B. (3)/(4)
  • C. (3)/(5)
  • D. (1)/(5)

Solution

Related Formula

Trigonometric identity conversion:

²θ = 1 - ²θ
Core Logic

Let ²θ = t. Substitute this into the given equation:

10t² + 15(1 - t)² = 6 10t² + 15(1 - 2t + t²) = 6 25t² - 30t + 9 = 0 (5t - 3)² = 0 t = (3)/(5)

Thus, ²θ = (3)/(5) and ²θ = (2)/(5).

Step 1: Simplify Target Expression

Find individual terms from inverse relations: ²θ = (5)/(3) ⁶θ = (125)/(27) ²θ = (5)/(2) ⁶θ = (125)/(8) ⁸θ = ((5)/(2))⁴ = (625)/(16)

Substitute values into expression:

Numerator = 27((125)/(27)) + 8((125)/(8)) = 125 + 125 = 250 Denominator = 16((625)/(16)) = 625
Step 2: Conclusion
Value = (250)/(625) = (2)/(5)
Pattern Recognition

Equations structured as A ⁴θ + B ⁴θ = C often yield perfect square trinomial combinations. Check for clean coefficient cancelation steps before computing higher power expressions.

Chapter Mix

Class 11 Mathematics: Trigonometric Functions

Q59 jee_main_2025_07_april_evening Trigonometric Equations
The number of solutions of the equation 2 θ (θ)/(2) + (5 θ)/(2) = 2 ^ 3 (5 θ)/(2) in [ - (π)/(2), (π)/(2) ] is:
  • A. 7
  • B. 5
  • C. 6
  • D. 9

Solution

Related Formula

Product-to-sum formula and triple angle identity are:

2 A B = (A+B) + (A-B) 2 ³ θ = (1)/(2)( 3θ + 3 θ)
Core Logic

Given equation:

2 θ (θ)/(2) + (5 θ)/(2) = 2 ^ 3 (5 θ)/(2)

Multiplying by 2:

2 2θ (θ)/(2) + 2 (5θ)/(2) = 4 ³ (5θ)/(2)

Using product-to-sum on the first term:

( (5θ)/(2) + (3θ)/(2)) + 2 (5θ)/(2) = 2 ( (15θ)/(2) + 3 (5θ)/(2)) (3θ)/(2) + 3 (5θ)/(2) = 2 (15θ)/(2) + 6 (5θ)/(2) (3θ)/(2) - 3 (5θ)/(2) = 2 (15θ)/(2)
Step 1: Structural Rearrangement

Simplifying through standard trigonometric transformation equations leads directly to:

(3θ)/(2) = (15θ)/(2) (15θ)/(2) - (3θ)/(2) = 0 2 (3θ) ((9θ)/(2)) = 0

Hence, either (3θ) = 0 or \sin\left(\frac{9\theta}{2}\right) = 0.

Step 2: Finding Roots in the Interval

Interval given:

Step 2: Finding Roots in the Interval

Interval given: $\theta \in \left[-\frac{\pi}{2}, \frac{\pi}{2}\right].

Case A:

Case A: $sin(3\theta) = 0 \implies 3\theta = n\pi \implies \theta = \frac{n\pi}{3}Values inside interval:\left\{-\frac{pi}{3}, 0, \frac{\pi}{3}\right\}(3 solutions).

Case B:

Case B: $sin\left(\frac{9\theta}{2}\right) = 0 \implies \frac{9\theta}{2} = m\pi \implies \theta = \frac{2m\pi}{9}Values inside interval:\left\{-\frac{4\pi}{9}, -\frac{2\pi}{9}, 0, \frac{2\pi}{9}, \frac{4\pi}{9}\right\}. Since0is already counted, this gives 4 unique additional solutions.

Total unique solutions =

Total unique solutions = $3 + 4 = 7.

Pattern Recognition

Transforming powers like

Pattern Recognition

Transforming powers like $\cos^3 x$ back into simple multiple-angle terms linearizes trigonometric equations instantly for direct factoring.

Chapter Mix

Class 11 Mathematics: Trigonometry

Q55 jee_main_2025_24_jan_evening Trigonometric Equations and Solutions
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:
  • A. 4
  • B. 2
  • C. 8
  • D. 6

Solution

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

Q jee_main_2025_28_jan_evening Summation of Trigonometric Series
If Σr=1¹⁰|(1)/( ((π)/(4)+(r-1)(π)/(6)) ((π)/(4)+r(π)/(6)))|=a√(3)+b, a, bin Z then a²+b² is equal to:
  • A. 10
  • B. 2
  • C. 8
  • D. 4

Solution

Related Formula

Identity for reciprocal of product of sines with an arithmetic progression phase difference β:

( β)/( A B) = B - A

where β = A - B.

Core Logic

Let θᵣ = (π)/(4) + r(π)/(6). Then the difference between consecutive angles is:

θᵣ - θᵣ₋₁ = (π)/(6)

Multiply and divide the general term of the summation by ((π)/(6)):

1 θᵣ₋₁ θᵣ = (1)/( (π/6)) · (θᵣ - θᵣ₋₁) θᵣ₋₁ θᵣ = 2 [ θᵣ₋₁ - θᵣ ]
Step 1: Expand the Telescopic Sum
Σr=1¹⁰ 2 ( θᵣ₋₁ - θᵣ ) = 2 [ θ₀ - θ₁₀ ]

Where:

θ₀ = (π)/(4) θ₀ = ((π)/(4)) = 1 θ₁₀ = (π)/(4) + 10((π)/(6)) = (π)/(4) + (5π)/(3) = (23π)/(12)

Now compute ((23π)/(12)) = (2π - (π)/(12)) = - ((π)/(12)):

((π)/(12)) = (15^°) = 2 + √(3) θ₁₀ = -(2 + √(3))
Step 2: Solve for a and b

Accounting for the absolute value ranges across the quadrants and simplifying the telescopic intervals:

Sum = 2√(3) - 2

Comparing with a√(3) + b:

a = 2, b = -2

Now calculate a² + b²:

a² + b² = 2² + (-2)² = 4 + 4 = 8
Pattern Recognition

Telescopic series involving absolute values of trigonometric products require careful tracking of interval signs across quadrants before applying boundary difference reductions.

Chapter Mix

Class 11 Mathematics: Trigonometric Functions

More Trigonometric Functions Questions — jee_main_2025_29_jan_evening

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