The Six Inverse Trigonometric Functions
Inverse trigonometric functions (also called arc-functions or anti-trigonometric functions) are the inverses of the standard trigonometric functions. They return the angle whose trig function value equals the input. Each has specific domain and range restrictions to ensure they are proper functions.
Summary of All Inverse Trig Functions
arcsin(x)
Domain: [-1, 1]. Range: [-π/2, π/2] or [-90°, 90°].
arccos(x)
Domain: [-1, 1]. Range: [0, π] or [0°, 180°].
arctan(x)
Domain: all reals. Range: (-π/2, π/2) or (-90°, 90°).
arccsc(x)
Domain: |x| ≥ 1. Range: [-π/2, π/2], x ≠ 0.
arcsec(x)
Domain: |x| ≥ 1. Range: [0, π], x ≠ π/2.
arccot(x)
Domain: all reals. Range: (0, π) or (0°, 180°).
Important Identities
Complementary Relationships
- arcsin(x) + arccos(x) = π/2 for all x in [-1, 1].
- arctan(x) + arccot(x) = π/2 for all real x.
- arcsec(x) + arccsc(x) = π/2 for all |x| ≥ 1.
Reciprocal Relationships
- arccsc(x) = arcsin(1/x) for |x| ≥ 1.
- arcsec(x) = arccos(1/x) for |x| ≥ 1.
- arccot(x) = arctan(1/x) for x > 0.
- arccot(x) = π + arctan(1/x) for x < 0.
Negative Argument Identities
- arcsin(-x) = -arcsin(x) (odd function).
- arccos(-x) = π - arccos(x).
- arctan(-x) = -arctan(x) (odd function).
- arccsc(-x) = -arccsc(x) (odd function).
- arcsec(-x) = π - arcsec(x).
- arccot(-x) = π - arccot(x).
Derivatives of Inverse Trig Functions
- d/dx arcsin(x) = 1/√(1 - x²)
- d/dx arccos(x) = -1/√(1 - x²)
- d/dx arctan(x) = 1/(1 + x²)
- d/dx arccsc(x) = -1/(|x|√(x² - 1))
- d/dx arcsec(x) = 1/(|x|√(x² - 1))
- d/dx arccot(x) = -1/(1 + x²)