Arccos (inverse cosine) returns the angle whose cosine equals the given value. It is the inverse function of cosine.

Why does arccos range from 0° to 180°?

This range ensures arccos is a proper function (one output per input). Cosine takes each value in [-1,1] exactly once in the interval [0°, 180°].

How are arcsin and arccos related?

arcsin(x) + arccos(x) = 90° for any x in [-1, 1]. They are complementary angles.

Inverse Cosine Calculator

Calculate the inverse cosine (arccos) of a value. Returns the angle whose cosine equals the input.

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Value (-1 to 1)

Angle Rad

1.04719755

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Inverse Cosine (Arccos)

Definition

arccos(x) = the angle whose cosine is x

Domain and Range

Domain: -1 ≤ x ≤ 1

Range: 0° to 180° (0 to pi radians)

Common Values

arccos(1) = 0°

arccos(0.5) = 60°

arccos(0) = 90°

arccos(-1) = 180°

Example Calculation

Find arccos(0.5).

01arccos(0.5) = pi/3 radians
02= 60 degrees
03Verification: cos(60°) = 0.5

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