Last updated: August 27, 2026.
The Atn function returns the arctangent of a numeric expression in radians.
Syntax
Atn(number)Examples
Atn(1) ' approximately 0.785398
Degrees: Atn([Ratio]) * 180 / (4 * Atn(1))
Angle: Atn([Opposite] / [Adjacent])Atn returns an angle between -π/2 and π/2. Guard against division by zero before calculating a ratio.
See the Microsoft VBA function reference.
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