Inverse Trigonometric Functions

Relation between inverse(x) and inverse(-x)

  • Inverse Trigonometric Functions deal with the angles formed when trigonometric ratios are given.
  • These functions are defined as the inverses of the trigonometric functions.

Properties of Inverse Trigonometric Functions

  • The input of an inverse trigonometric function is the ratio of two sides in a right triangle.
  • The output of an inverse trigonometric function is the angle opposite to that ratio.

Inverse Trigonometric Functions in terms of Sine

  • sin^(-1)(x) represents the angle whose sine is x.
  • The range of sin^(-1)(x) is [-π/2, π/2].

Inverse Trigonometric Functions in terms of Cosine

  • cos^(-1)(x) represents the angle whose cosine is x.
  • The range of cos^(-1)(x) is [0, π].

Inverse Trigonometric Functions in terms of Tangent

  • tan^(-1)(x) represents the angle whose tangent is x.
  • The range of tan^(-1)(x) is [-π/2, π/2].

Relation between inverse(x) and inverse(-x)

  • For any real number x, sin^(-1)(-x) = -sin^(-1)(x).
  • For any real number x, cos^(-1)(-x) = π - cos^(-1)(x).
  • For any real number x, tan^(-1)(-x) = -tan^(-1)(x).

Domain and Range of Inverse Trigonometric Functions

  • The domain of an inverse trigonometric function is the range of the corresponding trigonometric function.
  • The range of an inverse trigonometric function is the domain of the corresponding trigonometric function.

Domain and Range of sin^(-1)(x)

  • The domain of sin^(-1)(x) is [-1, 1].
  • The range of sin^(-1)(x) is [-π/2, π/2].

Domain and Range of cos^(-1)(x)

  • The domain of cos^(-1)(x) is [-1, 1].
  • The range of cos^(-1)(x) is [0, π].

Domain and Range of tan^(-1)(x)

  • The domain of tan^(-1)(x) is (-∞, ∞).
  • The range of tan^(-1)(x) is (-π/2, π/2).

Properties of Inverse Trigonometric Functions

  • The sum, difference, and product of two inverse trigonometric functions often involve identities and simplifications.
  • The composition of two inverse trigonometric functions can simplify to simpler forms.

Property 1: sin^(-1)(x) + cos^(-1)(x) = π/2

Property 2: sin^(-1)(x) - cos^(-1)(x) = π/2

Property 3: tan^(-1)(x) * cot^(-1)(x) = 1

Property 4: sin^(-1)(x) = cos^(-1)(√(1-x^2))

Property 5: cos(2tan^(-1)(x)) = 1/(1+x^2)

Property 6: sin(2sin^(-1)(x)) = 2x/√(1-x^2)

Simplifying Compositions of Inverse Trigonometric Functions

  • Compositions of inverse trigonometric functions typically simplify to simpler forms.
  • These simplifications can be derived using trigonometric identities.

Example: sin^(-1)(sin(x))

  • The composition of sin^(-1)(sin(x)) can be simplified.
  • If -π/2 ≤ x ≤ π/2, then sin^(-1)(sin(x)) simplifies to x.
  • If x < -π/2 or x > π/2, then sin^(-1)(sin(x)) simplifies to π - x.

Example: cos^(-1)(cos(x))

  • The composition of cos^(-1)(cos(x)) can be simplified.
  • If 0 ≤ x ≤ π, then cos^(-1)(cos(x)) simplifies to x.
  • If x < 0 or x > π, then cos^(-1)(cos(x)) simplifies to -x.

Evaluating Inverse Trigonometric Functions

  • The values of inverse trigonometric functions can be evaluated using special triangles or reference angles.
  • Calculators and tables can also be used to find approximate values.

Example: Evaluate sin^(-1)(1/2)

  • Using special triangles, we know that sin^(-1)(1/2) = π/6 or 30 degrees.

Example: Evaluate cos^(-1)(-1/2)

  • Using special triangles, we know that cos^(-1)(-1/2) = 2π/3 or 120 degrees.

Example: Evaluate tan^(-1)(√3)

  • Using reference angles, we know that tan^(-1)(√3) = π/3 or 60 degrees.

Graphs of Inverse Trigonometric Functions

  • The graphs of inverse trigonometric functions can be obtained by reflecting the graphs of the corresponding trigonometric functions in the line y = x.
  • The domain of the inverse trigonometric functions becomes the range of the corresponding trigonometric functions.

Graph of y = sin^(-1)(x)

  • The graph of y = sin^(-1)(x) is a quarter unit circle in the first and second quadrants.
  • The domain is [-1, 1] and the range is [-π/2, π/2].

Graph of y = cos^(-1)(x)

  • The graph of y = cos^(-1)(x) is a quarter unit circle in the first and fourth quadrants.
  • The domain is [-1, 1] and the range is [0, π].

Graphs of Inverse Trigonometric Functions (contd.)

Graph of y = tan^(-1)(x)

  • The graph of y = tan^(-1)(x) covers the entire plane, except for the vertical asymptotes x = π/2 and x = -π/2.
  • The domain is (-∞, ∞) and the range is (-π/2, π/2).

Graph of y = cot^(-1)(x)

  • The graph of y = cot^(-1)(x) covers the entire plane, except for the vertical asymptotes x = 0 and x = π.
  • The domain is (-∞, ∞) and the range is (0, π).

Inverse Trigonometric Functions in Terms of Other Functions

  • Inverse trigonometric functions can be expressed in terms of other trigonometric functions.
  • These expressions can be derived using trigonometric identities and algebraic manipulations.

Expressing sin^(-1)(x) in terms of cos^(-1)(x)

  • By using the identity sin^2(x) + cos^2(x) = 1, we can derive an expression for sin^(-1)(x) in terms of cos^(-1)(x) as sin^(-1)(x) = π/2 - cos^(-1)(x).

Expressing cos^(-1)(x) in terms of sin^(-1)(x)

  • By using the identity sin^2(x) + cos^2(x) = 1, we can derive an expression for cos^(-1)(x) in terms of sin^(-1)(x) as cos^(-1)(x) = π/2 - sin^(-1)(x).

Inverse Trigonometric Functions in Terms of Other Functions (contd.)

Expressing tan^(-1)(x) in terms of cos^(-1)(x)

  • By using the identity tan(x) = sin(x)/cos(x), we can derive an expression for tan^(-1)(x) in terms of cos^(-1)(x) as tan^(-1)(x) = sin^(-1)(x/sqrt(1+x^2)).

Expressing cot^(-1)(x) in terms of sin^(-1)(x)

  • By using the identity cot(x) = cos(x)/sin(x), we can derive an expression for cot^(-1)(x) in terms of sin^(-1)(x) as cot^(-1)(x) = sin^(-1)(1/x).

Applications of Inverse Trigonometric Functions

  • Inverse trigonometric functions have various applications in mathematics and physics.
  • They are used to solve problems involving angles, distances, and coordinates.

Example: Finding the angle of elevation

  • Inverse trigonometric functions are used to find the angle of elevation in problems involving heights or distances.

Example: Solving for unknown sides in right triangles

  • By applying inverse trigonometric functions, we can find the lengths of the unknown sides in right triangles.

Applications of Inverse Trigonometric Functions (contd.)

Example: Calculating coordinates

  • Inverse trigonometric functions are used to calculate the coordinates of a point given its distance and angle from the origin.

Example: Solving trigonometric equations

  • Inverse trigonometric functions are used to solve trigonometric equations involving unknown angles.

Inverse Trigonometric Functions - Relation between inverse(x) and inverse(-x)

  • For any real number x, sin^(-1)(-x) = -sin^(-1)(x).
  • For any real number x, cos^(-1)(-x) = π - cos^(-1)(x).
  • For any real number x, tan^(-1)(-x) = -tan^(-1)(x).

Example: Find sin^(-1)(-0.5)

  • sin^(-1)(-0.5) is equivalent to -sin^(-1)(0.5).
  • Using a calculator, we find that sin^(-1)(0.5) is approximately 0.524.
  • Therefore, sin^(-1)(-0.5) is approximately -0.524.

Example: Find cos^(-1)(-0.8)

  • cos^(-1)(-0.8) is equivalent to π - cos^(-1)(0.8).
  • Using a calculator, we find that cos^(-1)(0.8) is approximately 0.643.
  • Therefore, cos^(-1)(-0.8) is approximately π - 0.643 ≈ 2.498.

Example: Find tan^(-1)(-2)

  • tan^(-1)(-2) is equivalent to -tan^(-1)(2).
  • Using a calculator, we find that tan^(-1)(2) is approximately 1.107.
  • Therefore, tan^(-1)(-2) is approximately -1.107.

Inverse Trigonometric Functions - Domain and Range

  • The domain of an inverse trigonometric function is the range of the corresponding trigonometric function.
  • The range of an inverse trigonometric function is the domain of the corresponding trigonometric function.

Domain and Range of sin^(-1)(x)

  • The domain of sin^(-1)(x) is [-1, 1].
  • The range of sin^(-1)(x) is [-π/2, π/2].

Domain and Range of cos^(-1)(x)

  • The domain of cos^(-1)(x) is [-1, 1].
  • The range of cos^(-1)(x) is [0, π].

Domain and Range of tan^(-1)(x)

  • The domain of tan^(-1)(x) is (-∞, ∞).
  • The range of tan^(-1)(x) is (-π/2, π/2).

Example: Find the domain and range of sin^(-1)(x^2)

  • The domain is [0, 1] because x^2 can only be between 0 and 1.
  • The range is [0, π/2] because sin^(-1)(x) has a range of [-π/2, π/2].

Inverse Trigonometric Functions - Simplifying Compositions

  • Compositions of inverse trigonometric functions typically simplify to simpler forms.
  • These simplifications can be derived using trigonometric identities.

Example: Simplify sin^(-1)(sin(x))

  • If -π/2 ≤ x ≤ π/2, then sin^(-1)(sin(x)) simplifies to x.
  • If x < -π/2 or x > π/2, then sin^(-1)(sin(x)) simplifies to π - x.

Example: Simplify cos^(-1)(cos(x))

  • If 0 ≤ x ≤ π, then cos^(-1)(cos(x)) simplifies to x.
  • If x < 0 or x > π, then cos^(-1)(cos(x)) simplifies to -x.

Example: Simplify tan^(-1)(tan(x))

  • If -π/2 ≤ x ≤ π/2, then tan^(-1)(tan(x)) simplifies to x.
  • If x < -π/2 or x > π/2, then tan^(-1)(tan(x)) simplifies to x - π.

Example: Simplify sin^(-1)(cos(x))

  • There is no simplification for sin^(-1)(cos(x)). It remains as sin^(-1)(cos(x)).

Inverse Trigonometric Functions - Evaluating Values

  • The values of inverse trigonometric functions can be evaluated using special triangles or reference angles.
  • Calculators and tables can also be used to find approximate values.

Example: Evaluate sin^(-1)(1/2)

  • Using special triangles, we know that sin^(-1)(1/2) is equal to π/6 or approximately 0.524.

Example: Evaluate cos^(-1)(-0.5)

  • Using special triangles, we know that cos^(-1)(-0.5) is equal to π/3 or approximately 1.047.

Example: Evaluate tan^(-1)(√3)

  • Using reference angles, we know that tan^(-1)(√3) is equal to π/3 or approximately 1.047.

Example: Evaluate sin^(-1)(0)

  • The input of sin^(-1)(x) is the ratio of two sides in a right triangle.
  • Since sin(0) = 0, sin^(-1)(0) is equal to 0.

Inverse Trigonometric Functions - Graphs

  • The graphs of inverse trigonometric functions can be obtained by reflecting the graphs of the corresponding trigonometric functions in the line y = x.
  • The domain of the inverse trigonometric functions becomes the range of the corresponding trigonometric functions.

Graph of y = sin^(-1)(x)

  • The graph of y = sin^(-1)(x) is a quarter unit circle in the first and second quadrants.
  • The domain is [-1, 1] and the range is [-π/2, π/2].

Graph of y = cos^(-1)(x)

  • The graph of y = cos^(-1)(x) is a quarter unit circle in the first and fourth quadrants.
  • The domain is [-1, 1] and the range is [0, π].

Graph of y = tan^(-1)(x)

  • The graph of y = tan^(-1)(x) covers the entire plane, except for the vertical asymptotes x = π/2 and x = -π/2.
  • The domain is (-∞, ∞) and the range is (-π/2, π/2).

Inverse Trigonometric Functions - Graphs (contd.)

Graph of y = cot^(-1)(x)

  • The graph of y = cot^(-1)(x) covers the entire plane, except for the vertical asymptotes x = 0 and x = π.
  • The domain is (-∞, ∞) and the range is (0, π).

Example: Sketch the graph of y = sin^(-1)(x)

  • We know that the graph is a quarter unit circle in the first and second quadrants.
  • The domain is [-1, 1] and the range is [-π/2, π/2].

Example: Sketch the graph of y = tan^(-1)(x)

  • The graph covers the entire plane, except for the vertical asymptotes x = π/2 and x = -π/2.
  • The domain is (-∞, ∞) and the range is (-π/2, π/2).

Example: Sketch the graph of y = cos^(-1)(x)

  • The graph is a quarter unit circle in the first and fourth quadrants.
  • The domain is [-1, 1] and the range is [0, π].

Inverse Trigonometric Functions - Other Expressions

  • Inverse trigonometric functions can be expressed in terms of other trigonometric functions.
  • These expressions can be derived using trigonometric identities and algebraic manipulations.

Expressing sin^(-1)(x) in terms of cos^(-1)(