Let S = x: ⁻¹x = π + ⁻¹x + ⁻¹(2x + 1). Then Σxin S(2x - 1)² is equal to

Numerical Answer Type:
Enter a numerical value Answer: 5 +4 marks

Solution & Explanation

Related Formula
⁻¹ x + ⁻¹ x = (π)/(2) 2α = 2 ² α - 1
Core Logic

Rearrange using the principal trigonometric identity property ⁻¹ x = (π)/(2) - ⁻¹ x:

⁻¹ x = π + ((π)/(2) - ⁻¹ x) + ⁻¹(2x + 1) 2 ⁻¹ x - ⁻¹(2x + 1) = (3π)/(2)
Step 1: Isolate angles using variable substitution

Let ⁻¹ x = α and ⁻¹(2x + 1) = β.

2α - β = (3π)/(2) 2α = (3π)/(2) + β

Take cosine on both sides:

(2α) = ((3π)/(2) + β) = β
Step 2: Convert to algebraic identity form

Using double \angle formulas:

2 ² α - 1 = β

Since α = x and β = 2x + 1, substitute directly:

2x² - 1 = 2x + 1 2x² - 2x - 2 = 0 x² - x - 1 = 0

Solving the quadratic equation gives:

x = 1 ± √(5)2

Checking domain validation constraints for inverse functions dictates that only x = 1 - √(5)2 is valid (the positive root exceeds principal bounds).

Step 3: Evaluate target question calculation

From the valid root, we track:

2x - 1 = -√(5)

Squaring both sides yields:

(2x - 1)² = (-√(5))² = 5
Pattern Recognition

When inverse sums equate to values like (3π)/(2), look for extreme boundary values or domain constraints to eliminate invalid algebraic roots.

Chapter Mix

Class 12 Mathematics: Inverse Trigonometric Functions Class 11 Mathematics: Trigonometric Equations

Reference Study Guides

More Inverse Trigonometric Functions Previous-Year Questions — Page 9

Q15 jee_main_2024_31_jan_evening Trigonometric Equations
The number of solutions, of the equation ex - 2e- x = 2 is
  • A. 2
  • B. more than 2
  • C. 1
  • D. 0

Solution

Core Logic

Let ex = t, where t > 0 because exponential functions are strictly positive. Substitute into the equation:

t - (2)/(t) = 2 t² - 2t - 2 = 0

Solve for t using the quadratic formula:

t = 2 ± √(4 - 4(1)(-2))2 = 1 ± √(3)

Since t > 0, we discard 1 - √(3). Thus, t = 1 + √(3) ≈ 2.732. Now, equate back:

ex = 1 + √(3) x = ln(1 + √(3))

We know e ≈ 2.718. Since 1 + √(3) > e, it follows that ln(1 + √(3)) > 1. But the range of x is [-1, 1]. Therefore, x cannot equal a value strictly greater than 1. No real solution exists.

Chapter Mix

Class 11 Maths: Trigonometric Functions Class 12 Maths: Continuity and Differentiability

Q16 jee_main_2024_31_jan_evening Properties of ITFs
If a = ⁻¹( (5)) and b = ⁻¹( (5)), then a² + b² is equal to
  • A. 4π² + 25
  • B. 8π² - 40π + 50
  • C. 4π² - 20π + 50
  • D. 25

Solution

Related Formula
⁻¹( x) = x - 2π for x in [3π/2, 5π/2] ⁻¹( x) = 2π - x for x in [π, 2π]
Core Logic

Evaluate a = ⁻¹( 5): The principal branch of ⁻¹ x is [-π/2, π/2]. 5 radians is approximately 5 × 57.3^° ≈ 286.5^° (in 4th quadrant). The equivalent angle in the principal domain is 5 - 2π. Thus, a = 5 - 2π.

Evaluate b = ⁻¹( 5): The principal branch of ⁻¹ x is [0, π]. 5 radians is in [π, 2π]. The equivalent angle is 2π - 5. Thus, b = 2π - 5.

Calculate a² + b²:

a² + b² = (5 - 2π)² + (2π - 5)²

= 2(5 - 2π)²

= 2(25 + 4π² - 20π) = 8π² - 40π + 50
Chapter Mix

Class 12 Maths: Inverse Trigonometric Functions

Q15 jee_main_2024_31_jan_morning Properties of Inverse Trigonometric Functions
For α, β, γ ≠ 0. If ⁻¹α + ⁻¹β + ⁻¹γ = π and (α + β + γ)(α - γ + β) = 3 αβ then γ equal to
  • A. √(3)2
  • B. 1√(2)
  • C. √(3) - 12√(2)
  • D. √(3)

Solution

Core Logic

Let ⁻¹α = A, ⁻¹β = B, ⁻¹γ = C. Given A + B + C = π. Since A = α, B = β, C = γ, α, β, γ act like the side lengths of a triangle divided by 2R by Sine rule. However, directly dealing with the relation:

(α + β + γ)(α + β - γ) = 3αβ
Step 1: Simplify Algebraic Relation
(α + β)² - γ² = 3αβ α² + β² + 2αβ - γ² = 3αβ α² + β² - γ² = αβ
Step 2: Triangle Identification

Divide by 2αβ:

(α² + β² - γ²)/(2αβ) = (1)/(2)

By Cosine Rule, C = (1)/(2). Since C = ⁻¹γ, we know C = γ. C = √(1 - γ²) = (1)/(2).

Step 3: Final Solution
1 - γ² = (1)/(4) γ² = (3)/(4)

Since C is an angle of a triangle (or sum equals π and elements are positive limits), γ = C > 0.

γ = √(3)2
Pattern Recognition

The expression (α + β + γ)(α + β - γ) = 3αβ perfectly mirrors the Cosine Rule standard form giving C = 1/2.

Chapter Mix

Class 12 Maths: Inverse Trigonometric Functions Class 11 Maths: Trigonometric Functions

More Inverse Trigonometric Functions Questions — jee_main_2025_29_jan_morning

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