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All questions of Chapter 2 - Inverse Trigonometric Functions for JEE Exam

Can you explain the answer of this question below:

  • A:

    4

  • B:

    1/4

  • C:

    2

  • D:

    none of these.

The answer is a.

Divey Sethi answered
sin θ is 3/5.
on simplifying:
(secθ + tanθ)/(secθ - tanθ)
We get, (1+sin θ)/(1-sin θ)
=(1+3/5)/(1-3/5)
=(8/2)
=4

Evaluate sin(3 sin–10.4)
​a)0.56
b)0.31
c)0.64
d)0.9
Correct answer is 'D'. Can you explain this answer?

3sin^-1(x) = sin^-1(3x - 4x^3) when -1/2<=x<=1/2
Definitely 0.4 comes in this range of x and so
3sin^-1(0.4) = sin^-1[3*0.4 - 4*0.4^3]
3sin^-1(0.4) = sin^-1[1.2 - 4*0.064]
3sin^-1(0.4) = sin^-1[1.2 - 0.256]
3sin^-1(0.4) = sin^-1[0.944]
Finally , sin(3sin^-1(0.4)) = sin{sin^-1(0.944)} = 0.944

The maximum value of sin x + cos x is
  • a)
    1
  • b)
    2
  • c)
    √2
  • d)
Correct answer is option 'C'. Can you explain this answer?

Shreya Gupta answered
sinx + cosx=sinx + sin(90-x)=2sin{(x+90-x)/2}cos{(x-90+x)/2}using the formula 

The simplest form of for x > 0 is …​
  • a)
    x
  • b)
    -x/2
  • c)
    2x
  • d)
    x/2
Correct answer is option 'D'. Can you explain this answer?

Mira Joshi answered
tan-1(1-cosx/1+cosx)½
= tan-1{(2sin2 x/2) / (2cos2 x/2)}½
= tan-1{(2sin2 x/2) / (2cos2 x/2)}
= tan-1(tan x/2)
= x/2

Evaluate :cos (tan–1 x)
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'B'. Can you explain this answer?

Sushil Kumar answered
tan−1 x = θ , so that  x=tanθ . We need to determine  cosθ .
sec2θ = 1 + tan2θ = 1 + x2 
∴s ecθ = ±√(1+x2
Then, cos(tan−1x) = cosθ=1/secθ = ±1/√(1+x2)

  • a)
    4
  • b)
    1/4
  • c)
    2
  • d)
    none of these.
Correct answer is option 'A'. Can you explain this answer?

Krishna Iyer answered
sin θ is 3/5.
on simplifying:
(secθ + tanθ)/(secθ - tanθ)
We get, (1+sin θ)/(1-sin θ)
=(1+3/5)/(1-3/5)
=(8/2)
=4

The value ofcos150−sin150 is
  • a)
  • b)
  • c)
    0
  • d)
     
Correct answer is option 'D'. Can you explain this answer?

Poojan Angiras answered
Heyy!!! write cos 15 and sin 15 as cos(60-45) and sin(60-45) respectively.And then apply formula of cos(a+b) and sin(a+b).Proceed as the question u will get correct answer :-):-)^_^

If ab + bc + ca = 0, then find 1/a2-bc + 1/b2 – ca + 1/c2- ab
  • a)
    π
  • b)
    0
  • c)
    -1
  • d)
Correct answer is option 'B'. Can you explain this answer?

Preeti Iyer answered
Given ab+bc+ca=0 and asked to find value 1/(a2-bc ) + 1/(c2-ab) + 1/(a2-bc)Put -ac = ab + bc ; -ab = ac+ bc and -bc =ab + 

The number of solutions of the equation sin-1 x - cos-1 x = sin-1(1/2) is
a) 3
b) 1
c) 2
d) infinite.
Correct answer is option 'B'. Can you explain this answer?

Solution:

Given equation is sin^-1(x) - cos^-1(x) = sin^-1(1/2)

We know that sin(x) + cos(x) = √2 cos(x - π/4)

So, sin^-1(x) - cos^-1(x) = π/2 - sin^-1(√2x)

Therefore, the given equation becomes π/2 - sin^-1(√2x) = sin^-1(1/2)

sin(sin^-1(x)) = xsin(π/2 - sin^-1(√2x)) = √[1 - 2x^2]

√[1 - 2x^2] = 1/2

2x^2 = 3/4

x = ±√3/2

Therefore, the given equation has only 1 solution, which is x = √3/2 or x = -√3/2.

Hence, the correct answer is option B.

Evaluate: sin (2 sin–10.6)​
  • a)
    0.6
  • b)
    0.66
  • c)
    0.36
  • d)
    0.96
Correct answer is option 'D'. Can you explain this answer?

Nikita Singh answered
Let, sin-1(0.6) = A…………(1)
  ( Since, sin² A + cos² A = 1 ⇒ sin² A = 1 - cos² A ⇒ sin A = √(1-cos² A) )

  • a)
    ±√3.
  • b)
    0
  • c)
  • d)
    1
Correct answer is option 'D'. Can you explain this answer?

Devendra Singh answered
Apply apply formula of Sin inverse X + Cos inverse X and the question will be solved

  • a)
  • b)
    1
  • c)
    0
  • d)
    none of these.
Correct answer is option 'B'. Can you explain this answer?

Nikita Singh answered
sin-1√3/5 = A
Sin A = √3/5 , cos A = √22/5 
Therefore Cos-1√3/5 = B
Cos B = √3/5 , sin B = √22/5  
sin(A+B) = sinA cosB + cosA sinB
= √3/5 * √3/5 + √22/5 * √22/5
= 3/25 * 22/25
= 25/25 
= 1

Evaluate 
  • a)
  • b)
  • c)
  • d)
Correct answer is 'A'. Can you explain this answer?

Ritu Singh answered
Correct Answer :- a
Explanation : cos-1(12/13) + sin-1 (3/5)
⇒ sin-1 5/13 + sin-1 3/5 
Using the formula,  sin-1x +  sin-1y = sin-1( x√1-y² + y√1-x² )
⇒ sin-1 ( 5/13√1-9/25 + 3√1-25/169)
⇒ sin-1 ( 5/13 × 4/5 + 3/5 × 12/13)
⇒ sin-1 (30 + 36 / 65)
⇒ sin-1 (56/ 65)

  • a)
    4
  • b)
    1/4
  • c)
    2
  • d)
    none of these.
Correct answer is 'A'. Can you explain this answer?

SinQ is 3/5.
on simplifying:
(secQ+tanQ)/(secQ-tanQ)
We get...(1+sinQ)/(1-sinQ)
=(1+3/5)/(1-3/5)
=(8/2)
=4

The simplest form of 
  • a)
  • b)
  • c)
    2x
  • d)
Correct answer is option 'A'. Can you explain this answer?

Seelam Yogitha answered
Divide inner functions(both nr n Dr) with cosx,, tan^-(1-tanx/1+tanx)=tan^-(tan(π/4 -X) )=π/4 -x

Evaluate sin(3 sin–1 0.4)​
  • a)
    0.9
  • b)
    0.31
  • c)
    0.64
  • d)
    0.56
Correct answer is option 'D'. Can you explain this answer?

Mira Sharma answered
sin(3 sin^−1 0.4)
= sin[sin^−1(3 x 0.4−4 x 0.4^2)]      [∵3sin^−1 x = sin^−1(3x − 4x^3)]
= sin[sin^−1(1.2 − 4 x 0.16)]
= sin[sin^−1(1.2 − 0.64)]
= sin[sin^−1(0.56)] = 0.56

 is equal to
  • a)
  • b)
  • c)
  • d)
Correct answer is 'C'. Can you explain this answer?

Nikita Singh answered
Let y = tan−1[(a−x)/(a+x)]1/2
put x = a cos θ
Now, y = tan−1[(a − a cos θ)/(a + a cos θ)]1/2
⇒ y = tan−1((1 − cos θ)/(1 + cos θ))1/2
⇒ y = tan−1[[(1−cos θ)(1−cos θ)]/(1+cos θ)(1−cos θ)]1/2
⇒ y = tan−1[(1−cos θ)2/1 − cos2θ]1/2
⇒ y = tan−1[(1 − cos θ)/sin θ]
⇒ y = tan−1[2 sin2(θ/2)/2 sin(θ/2) . cos(θ/2)]
⇒ y = tan−1[tan(θ/2)]
⇒ y = θ/2
⇒ y = 1/2 cos−1(x/a)

Value of 
  • a)
  • b)
    tan-1 3 + tan-1 2x.
  • c)
  • d)
    tan-1 6 + tan-1 x.
Correct answer is option 'A'. Can you explain this answer?

Tejas Verma answered
tan-1[(3+2x)/(2-3x)]
=> tan-1[2(3/2 + x)/2(1-3/2x)]
=> tan-1[(3/2 + x)/(1-3/2x)]
=> tan-1(3/2) + tan-1(x)

sin (200)0 + cos (200)0 is
  • a)
    Zero
  • b)
    Positive
  • c)
    Zero or positive.
  • d)
    Negative
Correct answer is option 'D'. Can you explain this answer?

Dipika Dey answered
To determine the sign of sin(200)0 and cos(200)0, we need to recall the unit circle and the values of sine and cosine for angles in the different quadrants.

The unit circle is a circle with a radius of 1 unit, centered at the origin (0,0) on a coordinate plane. It helps us understand the relationship between angles and the coordinates on the circle.

The circle is divided into four quadrants: Quadrant I (0°-90°), Quadrant II (90°-180°), Quadrant III (180°-270°), and Quadrant IV (270°-360°).

In Quadrant I, both the x-coordinate (cosine) and the y-coordinate (sine) are positive. In Quadrant II, the x-coordinate (cosine) is negative, but the y-coordinate (sine) is positive. In Quadrant III, both the x-coordinate (cosine) and the y-coordinate (sine) are negative. In Quadrant IV, the x-coordinate (cosine) is positive, but the y-coordinate (sine) is negative.

Now let's consider the given angle, 200°.

Since 200° is greater than 180°, it lies in Quadrant III.

- The cosine of 200° will be negative because it is in Quadrant III.
- The sine of 200° will also be negative because it is in Quadrant III.

Hence, sin(200)0 and cos(200)0 are both negative.

Therefore, the correct answer is option 'D' - Negative.

If sin A + cos A = 1, then sin 2A is equal to
  • a)
    2
  • b)
    0
  • c)
    1/2
  • d)
    1
Correct answer is option 'B'. Can you explain this answer?

Anjali Sen answered
Understanding the Given Equation
We start with the equation:
- sinA + cosA = 1
This can be analyzed using the Pythagorean identity for sine and cosine.
Squaring Both Sides
If we square both sides:
- (sinA + cosA)^2 = 1^2
- sin²A + 2sinAcosA + cos²A = 1
Using the identity sin²A + cos²A = 1, we replace it in the equation:
- 1 + 2sinAcosA = 1
This simplifies to:
- 2sinAcosA = 0
Finding Values of Sine and Cosine
From 2sinAcosA = 0, we can conclude:
- sinA = 0 or cosA = 0
This means A can be:
- A = nπ (where n is an integer) for sinA = 0.
- A = π/2 + nπ for cosA = 0.
Calculating Sin 2A
We know that:
- sin 2A = 2sinAcosA
Given that either sinA = 0 or cosA = 0, we have:
- If sinA = 0, then sin 2A = 2 * 0 * cosA = 0.
- If cosA = 0, then sin 2A = 2 * sinA * 0 = 0.
In both scenarios, we find that:
- sin 2A = 0
Conclusion
Thus, the value of sin 2A is:
- 0
Therefore, the correct answer is option 'B'.

If 2tan−1(cos x) = tan−1(2cosecx) , then x =
  • a)
  • b)
  • c)
  • d)
    none of these.
Correct answer is option 'B'. Can you explain this answer?

If 2 tan-1 (cos x) = tan -1(2 cosec x),
2tan-1(cos x) = tan-1 (2 cosec x)
= tan-1(2 cosec x) 
= cot x cosec x = cosec x = x = π/4

Direction: Read the following text and answer the following questions on the basis of the same:
The value of an inverse trigonometric functions which lies in the range of Principal branch is called the principal value of that inverse trigonometric functions.
Principal value of cot-1(√3) is :
  • a)
    π/3
  • b)
    π
  • c)
    π/6
  • d)
    π/2
Correct answer is option 'C'. Can you explain this answer?

Disha Reddy answered
Understanding Principal Values of Inverse Trigonometric Functions
The principal value of an inverse trigonometric function is the value that lies within a specific range, typically chosen to make the function single-valued. For cotangent, the principal value is defined in the range (0, π).
Evaluating cot-1(√3)
To find the principal value of cot-1(√3), we need to determine the angle θ such that:
- cot(θ) = √3
Identifying the Angle
- The cotangent function is defined as the ratio of cosine to sine: cot(θ) = cos(θ)/sin(θ).
- We know that cot(π/6) = √3. This is because:
- In a 30-60-90 triangle, the adjacent side (cos) is √3, and the opposite side (sin) is 1.
Conclusion
- Therefore, when θ = π/6, cot(θ) yields √3.
- Since π/6 lies within the principal value range of (0, π), the answer for cot-1(√3) is indeed:
Correct Answer: Option C - π/6

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