Arccos of 1/3

Arcsin, Arccos, Arctan, Arccot
Function
x

What is arccos(1/3)?

Answer

arccos(1/3) ≈
70.5288° ≈ 1.2310 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.

arccos(1/3) is the angle α in [0°, 180°] with cos α = 1/3.

cos 70.5288° ≈ 0.3333

xyOP

α = arccos(1/3) ≈ 70.5288°

P ≈ (0.3333, 0.9428)

P lies on the line x = 1/3 in the upper half of the circle, where sin α ≥ 0; highlighted: cos α = 1/3.

All four inverse functions of 1/3
FunctionDegreesRadians
arcsin(1/3)≈ 19.4712°≈ 0.3398
arccos(1/3)≈ 70.5288°≈ 1.2310
arctan(1/3)≈ 18.4349°≈ 0.3218
arccot(1/3)≈ 71.5651°≈ 1.2490

See Also

FAQ

What is arccos(1/3)?

arccos(1/3) ≈ 70.5288° ≈ 1.2310 rad

How to convert arccos(1/3) to radians?

Multiply the angle in degrees by π/180: 70.5288° × π/180 ≈ 1.2310 rad.

Why does a calculator show 1.2310 for arccos(1/3)?

The calculator is in radian mode (RAD) and gives the angle in radians: arccos(1/3) ≈ 1.2310 rad. In degrees (DEG) it is ≈ 70.5288°.