Python acos(x) method return the arccosine value of x[-1,1], in radians.
>>> import math >>> math.acos(0.5)
1.0471975511965979
>>> math.acos(-1)
3.141592653589793
>>> math.acos(0)
1.5707963267948966
| Y (Degrees) | Y (Radian) | X |
| 180 ̊ | π | -1 |
| 150 ̊ | 5π/6 | -0.866025 |
| 135 ̊ | 3π/4 | -0.707107 |
| 120 ̊ | 2π/3 | -0.5 |
| 90 ̊ | π/2 | 0 |
| 60 ̊ | π/3 | 0.5 |
| 45 ̊ | π/4 | 0.707107 |
| 30 ̊ | π/6 | 0.866025 |
| 0 ̊ | 0 | 1 |
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