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Math function
ATAN
Returns the arctangent of a number, in radians.
Rarely usedDifficulty 1250 · ProficientUsage rank #276 of 520
When to use it
Inverse tangent: the angle in radians whose tangent is the argument, between -pi/2 and pi/2. Turn a slope into an angle.
The shape of it
- Syntax
=ATAN(number)
Worked examples
Slope of one
=ATAN(1) → 0.785398163
Pi over four.
In degrees
=DEGREES(ATAN(1)) → 45
In degrees.
Grade to angle
=DEGREES(ATAN(0.5)) → 26.56505118
A 50% grade is about 26.6°.
Worth knowing
- Use ATAN2 when you have x and y separately; it handles the quadrant and x = 0.
- Road grade in percent to degrees: DEGREES(ATAN(grade/100)).
- Convert with DEGREES.
Where it goes wrong
- ATAN(y/x) loses the quadrant and fails when x is 0.
- Returns radians.
Related
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