Apprendimento della Matematica

Identità Trigonometriche Inverse

Comprendere e applicare identità trigonometriche inverse

Interactive Inverse Trigonometric Identities Visualization

Welcome to the Inverse Trigonometric Identities Explorer

This interactive visualization helps you understand inverse trigonometric identities and their domain restrictions. Explore how inverse functions interact with their original functions and discover complementary relationships.

What you can explore:

  • Composition Identities - arcsin(sin(x)), sin(arcsin(x)), etc.
  • Complementary Identities - arcsin(x) + arccos(x) = π/2
  • Sum Formulas - arctan(x) + arctan(y) identities
  • Domain Restrictions - Why identities only hold for certain values

How to Use This Visualization

Interactive Features:

  • Select Identity - Choose from 9 different identities
  • Adjust x Value - Change input to see when identity holds
  • Adjust y Value - For sum formulas, change second input
  • Toggle Graph - Show/hide the graphical representation

What You'll See:

  • Left Side (Green) - The left-hand side of the identity
  • Right Side (Blue, Dashed) - The right-hand side
  • Equality Check - Whether LHS = RHS at current x
  • Domain Restrictions - When the identity holds

arcsin undoes sin, but only for restricted domain

Only equals x when x ∈ [-π/2, π/2]

Left Side (LHS)
Right Side (RHS)

Identity Evaluation

Identity:

arcsin(sin(x)) = x (for x ∈ [-π/2, π/2])

Left Side (LHS)

0.5000

≈ 28.65°

Right Side (RHS)

0.5000

≈ 28.65°

✓ Identity Holds

Key Concepts

Composition: f(f⁻¹(x)) = x always holds, but f⁻¹(f(x)) = x only when x is in the restricted domain.

Domain Restrictions: Inverse functions are defined on restricted domains to ensure they are one-to-one.

Complementary: arcsin(x) + arccos(x) = π/2 because sin and cos are complementary in a right triangle.

Common Identities

• sin(arcsin(x)) = x, x ∈ [-1, 1]

• arcsin(sin(x)) = x, x ∈ [-π/2, π/2]

• arccos(cos(x)) = x, x ∈ [0, π]

• arctan(tan(x)) = x, x ∈ (-π/2, π/2)

• arcsin(x) + arccos(x) = π/2

• arctan(x) + arctan(1/x) = π/2, x > 0

Understanding Domain Restrictions

Why arcsin(sin(x)) ≠ x for all x?

The sine function is not one-to-one (multiple x values give the same sin(x)). arcsin is defined to return values in [-π/2, π/2]. So arcsin(sin(π)) = arcsin(0) = 0, not π.

Why sin(arcsin(x)) = x always?

arcsin(x) always returns a value in [-π/2, π/2], and sin is one-to-one on this interval, so sin(arcsin(x)) = x for all x in the domain of arcsin (which is [-1, 1]).

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Identità Trigonometriche Inverse | Maths Learning