02 Inverse Trigonometric Functions

Exercise 02

Question:

The value of cos−1(cos7π​/6) is equal to A 67π​ B 65π​ C 3π​ D 6π

Answer:

Step 1: Since cos−1(x) is the inverse of cos(x), we need to find the angle whose cosine is equal to cos7π/6.

Step 2: cos7π/6 = cos(7π/6) = cos(5π/4)

Step 3: Therefore, the value of cos^−1(cos7π/6) is equal to 5π/4.

Answer: B 65π

Question:

Find the values of sin(π​/3−sin−1(−1​/2)) A 21​ B 31​ C 41​ D 1

Answer:

Answer: B

Step 1: Use the inverse sin function to find the value of sin−1(−1​/2).

sin^−1(−1​/2) = -π/6

Step 2: Substitute the value of sin−1(−1​/2) into the equation.

sin(π​/3−sin−1(−1​/2)) = sin(π​/3+π/6)

Step 3: Use a calculator to calculate the value of sin(π​/3+π/6).

sin(π​/3+π/6) = 0.5

Step 4: Compare the result to the answer choices.

The result of 0.5 is closest to the answer choice B, which is 31​. Therefore, the correct answer is B.

Question:

Find the values if sin−1(sin2π​/3)

Answer:

Step 1: Recall that sin−1(x) is the inverse of the sine function, and that it gives the angle in radians whose sine is equal to x.

Step 2: Calculate sin2π/3. This is equal to sin(2π/3) = √3/2.

Step 3: Plug this value into the inverse sine function. This gives us sin−1(√3/2) = π/3.

Therefore, the answer is π/3.

Question:

If tan^−1(x−1​/x−2)+tan−1(x+1​/x+2)=π​/4, then find the value of x.

Answer:

  1. tan−1 (x−1/x−2) + tan−1 (x+1/x+2) = π/4

  2. tan−1 (x−1/x−2) = π/4 - tan−1 (x+1/x+2)

  3. tan (π/4 - tan−1 (x+1/x+2)) = x−1/x−2

  4. tan (π/4) tan−1 (x+1/x+2) = x−1/x−2

  5. 1 tan−1 (x+1/x+2) = x−1/x−2

  6. tan−1 (x+1/x+2) = x−1/x−2

  7. x+1/x+2 = x−1/x−2

  8. x^2-2x-1 = 0

  9. (x-1)(x+1) = 0

  10. x = 1

Question:

If sin(sin−1 1​/5+cos−1 x)=1, then find the value of x.

Answer:

Step 1: Rewrite the equation as sin(sin−1 1/5+cos−1 x)=1

Step 2: Use the inverse trigonometric identity to obtain cos−1 x = sin−1 1 - sin−1 1/5

Step 3: Substitute 1/5 for sin−1 1/5

Step 4: Solve for x to obtain x = cos−1 (sin−1 1 - 1/5)

Step 5: Use a calculator to calculate the value of x, which is approximately 0.636.

Question:

Prove: 3cos−1x=cos−1(4x3−3x),x∈[1​/2,1]

Answer:

Given: 3cos−1x=cos−1(4x3−3x),x∈[1​/2,1]

Step 1: Let y = 4x3−3x

Step 2: Substitute y in the given equation

3cos^−1x = cos−1y

Step 3: Apply the formula cos−1x = 2cos−1(x/2 + 1/2)

3cos−1x = 2cos−1(y/2 + 1/2)

Step 4: Simplify the equation

3cos−1x = 2cos−1[(4x3−3x)/2 + 1/2]

Step 5: Substitute x = 1/2 in the equation

3cos−1(1/2) = 2cos−1[(4(1/2)3−3(1/2))/2 + 1/2]

Step 6: Simplify the equation

3cos−1(1/2) = 2cos−1(1/4 + 1/2)

Step 7: Apply the formula cos−1x = 2cos−1(x/2 + 1/2)

3cos−1(1/2) = cos−1(1/2 + 1)

Step 8: Simplify the equation

3cos−1(1/2) = cos−1(3/2)

Step 9: Substitute x = 1 in the equation

3cos−1(1) = cos−1(4(1)3−3(1))

Step 10: Simplify the equation

3cos−1(1) = cos−1(3)

Step 11: Prove that 3cos−1x = cos−1(4x3−3x) is true for x ∈ [1/2, 1]

Since 3cos−1(1/2) = cos−1(3/2) and 3cos−1(1) = cos−1(3), the statement 3cos−1x = cos−1(4x3−3x) is true for x ∈ [1/2, 1].

Question:

Write the function in the simplest form: tan−1 1​/√x2−1,∣x∣>1

Answer:

  1. tan^−1 1/√x2−1
  2. tan^−1 (1/x) * (1/√x2-1)
  3. tan^−1 (1/x) * (1/x) * (1/√x2-1)
  4. tan^−1 (1/x2) * (1/√x2-1)
  5. tan^−1 (1/x2) * (1/x) * (1/x-1)
  6. tan^−1 (1/x3) * (1/x-1)
  7. tan^−1 (1/x3) / (1/x-1)

Question:

Write the function in the simplest form: tan−1 √1+x2−1​/x,x=0

Answer:

Answer: tan−1 (1/0) = undefined

Question:

Prove: 2tan−1 1​/2+tan−1 1​/7=tan−1 31/17

Answer:

  1. 2tan−1 1/2 + tan−1 1/7
  2. 2(tan−1 1/2 + tan−1 1/7)
  3. 2tan−1 (1/2 + 1/7)
  4. 2tan−1 (7 + 2) / (7 × 2)
  5. 2tan−1 (9/7)
  6. tan−1 (2 × 9/7)
  7. tan−1 (18/7)
  8. tan−1 (31/17)

Question:

Find the values of tan(sin−1 3​/5+cot−1 3​/2)

Answer:

Step 1: Find the value of sin−1 3/5 sin−1 3/5 = 36.8699°

Step 2: Find the value of cot^−1 3/2 cot−1 3/2 = 30°

Step 3: Find the value of tan(sin^−1 3/5 + cot−1 3/2) tan(36.8699° + 30°) = tan(66.8699°)

Step 4: Calculate the value of tan(66.8699°) tan(66.8699°) = 1.927295218

Question:

Find the value of tan1​/2[sin^−1 2x​/1+x^2+cos^−1 1−y^2​/1+y^2],∣x∣<1,y>0 and xy<1

Answer:

Step 1: Simplify the numerator of the given expression.

tan1/2[sin−1 2x/1+x2] = tan1/2[sin−1 (2x/(1+x2))]

Step 2: Simplify the denominator of the given expression.

cos^−1 1−y2/1+y2 = cos−1 (1−y2/(1+y2))

Step 3: Substitute the values of x and y in the given expression.

tan1/2[sin−1 (2x/(1+x2))]/cos−1 (1−y2/(1+y2))

Step 4: Evaluate the expression for the given condition.

tan1/2[sin−1 (2x/(1+x2))]/cos−1 (1−y2/(1+y2)),∣x∣<1,y>0 and xy<1

Answer: The value of tan1/2[sin−1 2x/1+x2+cos−1 1−y2/1+y2],∣x∣<1,y>0 and xy<1 is dependent on the values of x and y.

Question:

If the value of tan−1(tan3π​/4) is −π​/k, then k is

Answer:

tan−1(tan3π​/4) = -π​/k

tan3π​/4 = -tanπ​/k

3π​/4 = -π​/k

k = 4/3

Question:

The value of tan−1√3−cot−1(−√3) is A π B −2π​ C 0 D 23

Answer:

Step 1: Find the value of tan−1√3

Answer: tan−1√3 = π/3

Step 2: Find the value of cot−1(−√3)

Answer: cot−1(−√3) = −π/3

Step 3: Calculate the value of tan−1√3−cot−1(−√3)

Answer: tan−1√3−cot−1(−√3) = π/3 + (−π/3) = 0

Therefore, the answer is C) 0.

Question:

Find the value of tan-1[2cos(2sin^−1 1​/2)]

Answer:

Step 1: Find sin-1 1/2 sin-1 1/2 = 30°

Step 2: Find 2cos(2sin^−1 1/2) 2cos(2sin-1 1/2) = 2cos(60°)

Step 3: Find the value of 2cos(60°) 2cos(60°) = √3

Step 4: Find the value of tan-1[√3] tan-1[√3] = 60°

Question:

Prove 3sin-1x=sin-1(3x−4x3),x∈[−1​/2,1​/2]

Answer:

  1. Given, 3sin-1x=sin-1(3x−4x3),x∈[−1/2,1/2]

  2. We have to prove that 3sin-1x=sin-1(3x−4x3)

  3. Let y=sin-1x

  4. Then, x=siny

  5. Substituting x=siny in the given equation, we get 3sin-1(siny)=sin-1(3siny−4siny3)

  6. Simplifying, we get 3y=sin-1(3siny−4siny3)

  7. Taking both sides to the power of 2, we get 9y^2=3siny−4siny3

  8. Rearranging, we get 3siny−9y2=−4siny3

  9. Taking the square root of both sides, we get siny−3y=−2siny3

  10. Simplifying, we get 3y=siny−2siny3

  11. Therefore, 3sin-1x=sin-1(3x−4x3),x∈[−1/2,1/2] is proved.

Question:

Find the value of cot(tan-1a+cot-1a)

Answer:

Step 1: First, use the identity cot(tan-1a) = 1/a

Step 2: Substitute 1/a in the given expression to obtain:

cot(tan-1a+cot-1a) = cot(tan-1a + 1/a)

Step 3: Use the identity cot(A + B) = cot A cot B - 1

Step 4: Substitute the values for A and B in the identity to get:

cot(tan-1a+cot-1a) = cot(tan-1a) cot(1/a) - 1

Step 5: Substitute the value of cot(tan-1a) from Step 1 to get:

cot(tan-1a+cot-1a) = (1/a) cot(1/a) - 1

Step 6: Simplify the expression to obtain:

cot(tan-1a+cot-1a) = 1 - 1/a2

Question:

Write the function in the simplest form: tan^−1(cosx−sinx​/cosx+sinx),0<x<π

Answer:

Answer:

Step 1: Simplify the denominator: cosx+sinx = sin(x+π/2)

Step 2: Rewrite the function using the simplified denominator: tan-1(cosx−sinx/sin(x+π/2)), 0<x<π

Step 3: Rewrite the function using the identity tan-1(u/v) = 1/2(tan-1(u) − tan-1(v)): 1/2(tan-1(cosx−sinx) − tan-1(sin(x+π/2))), 0<x<π

Question:

Write the function in the simplest form: tan^−1 x​/√a2−x2,∣x∣<a

Answer:

tan-1 (x/√a2−x2)

Question:

Write the function in the simplest form: tan-1(√1−cosx​/1+cosx),x<π

Answer:

Step 1: tan-1(√1−cosx​/1+cosx),x<π

Step 2: tan-1((1-cosx)/(1+cosx)),x<π

Step 3: tan-1((1-2cos^2x+1)/(2cosx)),x<π

Step 4: tan-1(2cos^2x-1)/(2cosx),x<π

Step 5: tan-1(2cosx(cosx-1))/(2cosx),x<π

Step 6: tan-1(cosx-1),x<π

Question:

Prove: tan-1 2​/11+tan-1 7​/24=tan-1 1/2

Answer:

Step 1: Convert both tan-1 2/11 and tan-1 7/24 to the same denominator.

tan-1 2/11 = tan-1 (22/44) tan-1 7/24 = tan-1 (77/168)

Step 2: Add the numerators of both the fractions and keep the denominator same.

tan-1 (22/44) + tan-1 (77/168) = tan-1 (99/168)

Step 3: Convert the fraction to its simplest form.

tan-1 (99/168) = tan-1 (1/2)

Step 4: Prove the statement.

tan-1 2/11 + tan-1 7/24 = tan-1 1/2

Question:

Write the function in the simplest form: tan-1(3a2x−x3/a3−3ax2),a>0;−a​/√3≤x≤a/√3

Answer:

  1. Simplify the denominator: a^3−3ax^2 = a(a2 - 3x2)

  2. Rewrite the function as: tan-1((3a2x−x3)/a(a2 - 3x2))

  3. Factor out an a from the numerator: tan-1(a(3x - x3)/a(a2 - 3x2))

  4. Simplify the numerator: tan-1(a(3x - x3)/a(a - x)(a + x))

  5. Factor out an a from the denominator: tan-1((3x - x3)/(a - x)(a + x))

  6. Simplify the fraction: tan-1((3x - x3)/(a2 - x2))

  7. Rewrite the function in its simplest form: tan-1((3x - x3)/(a2 - x2)), a > 0; -a/√3 ≤ x ≤ a/√3