Arccos of 2/5
Arcsin, Arccos, Arctan, Arccot
What is arccos(2/5)?
Answer
arccos(2/5) ≈
66.4218° ≈ 1.1593 rad
Range: arccos x is an angle from 0° to 180°, so the answer is unique.
≈ — the value is not a table one; rounded to 4 decimal places.
2/5 = 0.4.
arccos(2/5) is the angle α in [0°, 180°] with cos α = 2/5.
cos 66.4218° ≈ 0.4000
α = arccos(2/5) ≈ 66.4218°
P ≈ (0.4, 0.9165)
P lies on the line x = 2/5 in the upper half of the circle, where sin α ≥ 0; highlighted: cos α = 2/5.
| Function | Degrees | Radians |
|---|---|---|
| arcsin(2/5) | ≈ 23.5782° | ≈ 0.4115 |
| arccos(2/5) | ≈ 66.4218° | ≈ 1.1593 |
| arctan(2/5) | ≈ 21.8014° | ≈ 0.3805 |
| arccot(2/5) | ≈ 68.1986° | ≈ 1.1903 |
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See Also
- Sin, Cos, Tan, Cot of an Angle - Exact value in square roots and the decimal, with reduction to an acute angle on the unit circle
- Square Root Calculator - Calculate the square root of any number
- Simplify Square Root Calculator - Write any square root in simplest radical form, step by step
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<a href="https://calculat.io/en/number/inverse-trigonometry/arccos--2-5">Arccos of 2/5 (Inverse Cosine) in Degrees and Radians</a>Facebook
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![Arccos of 2/5 (Inverse Cosine) in Degrees and Radians. arccos(2/5) ≈ 66.4218° ≈ 1.1593 rad: the angle in [0°, 180°] whose cosine is 2/5. With the check and the unit circle.](https://calculat.io/en/number/inverse-trigonometry/arccos--2-5/generated.jpg)
Arccosine of nearby values
| x | arccos x |
|---|---|
| 1/4 | ≈ 75.5225° |
| 0.3 | ≈ 72.5424° |
| 1/3 | ≈ 70.5288° |
| 2/5 | ≈ 66.4218° |
| 1/2 | 60° = π/3 |
| 0.55 | ≈ 56.6330° |
| 4/7 | ≈ 55.1501° |