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    Cot 81 Degrees

    Sin, Cos, Tan, Cot of an Angle
    Function
    Angle (°)

    What is cot 81°?

    Answer

    cot 81° ≈
    0.1584

    Angle in radians: 81° = 9π/20. The point of the angle is in quadrant I, where cotangent is positive.

    ≈ — rounded to 4 decimal places. An exact form of cot 81° in square roots exists, but it is unwieldy — nested radicals.

    cot 81° = cos 81° / sin 81° ≈ 0.1584

    xyOP

    P(cos 81°, sin 81°) ≈ (0.1564, 0.9877)

    C(cot 81°, 1) ≈ (0.1584, 1) — where line OP meets the line y = 1.

    All four functions of 81°
    FunctionExact valueDecimal
    sin 81°—≈ 0.9877
    cos 81°—≈ 0.1564
    tan 81°—≈ 6.3138
    cot 81°—≈ 0.1584

    See Also

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    https://calculat.io/en/number/trigonometry/cot--81Copy
    <a href="https://calculat.io/en/number/trigonometry/cot--81">Cot 81 Degrees: Cotangent of 81° on the Unit Circle</a>Copy
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    Cot 81 Degrees: Cotangent of 81° on the Unit Circle. cot 81° ≈ 0.1584. The cotangent is the ratio x/y of the point at 81° on the unit circle.
    https://calculat.io/en/number/trigonometry/cot--81/generated.jpgCopy

    Cotangent of nearby angles

    Anglecot
    78°≈ 0.2126
    79°≈ 0.1944
    80°≈ 0.1763
    81°≈ 0.1584
    82°≈ 0.1405
    83°≈ 0.1228
    84°≈ 0.1051
    Recalculate with different values ↑

    FAQ

    What is cot 81°?

    cot 81° ≈ 0.1584

    Is there an exact value of cot 81°?

    Yes: 81° is a multiple of 3°, and the values of such angles can be written with square roots — but the expression is unwieldy, with nested radicals built from the values of 18° and 15° (3° = 18° − 15°). In practice the decimal is used: cot 81° ≈ 0.1584.

    Why does a calculator show −1.2331 for cot 81?

    The calculator is in radian mode (RAD): it takes cot 81 as the cotangent of 81 radians, cot 81 rad ≈ −1.2331. Switch it to degrees (DEG): cot 81° ≈ 0.1584. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also