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    Cos 80 Degrees

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

    What is cos 80°?

    Answer

    cos 80° ≈
    0.1736

    Angle in radians: 80° = 4π/9. The point of the angle is in quadrant I, where cosine is positive.

    ≈ — rounded to 4 decimal places. cos 80° can't be written with square roots: 80° is not a multiple of 3°.

    P(cos 80°, sin 80°) ≈ (0.1736, 0.9848)

    xyOP

    P(cos 80°, sin 80°) ≈ (0.1736, 0.9848)

    Highlighted: the projection on the x-axis — cosine, x ≈ 0.1736.

    All four functions of 80°
    FunctionExact valueDecimal
    sin 80°—≈ 0.9848
    cos 80°—≈ 0.1736
    tan 80°—≈ 5.6713
    cot 80°—≈ 0.1763

    See Also

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    https://calculat.io/en/number/trigonometry/cos--80Copy
    <a href="https://calculat.io/en/number/trigonometry/cos--80">Cos 80 Degrees: Cosine of 80° on the Unit Circle</a>Copy
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    Cos 80 Degrees: Cosine of 80° on the Unit Circle. cos 80° ≈ 0.1736. The cosine is the x-coordinate of the point at 80° on the unit circle.
    https://calculat.io/en/number/trigonometry/cos--80/generated.jpgCopy

    Cosine of nearby angles

    Anglecos
    77°≈ 0.2250
    78°≈ 0.2079
    79°≈ 0.1908
    80°≈ 0.1736
    81°≈ 0.1564
    82°≈ 0.1392
    83°≈ 0.1219
    Recalculate with different values ↑

    FAQ

    What is cos 80°?

    cos 80° ≈ 0.1736

    Why does cos 80° have no exact value?

    A trigonometric value of a whole number of degrees can be written with square roots only when the angle is a multiple of 3°. 80° is not, so no such exact form exists; the value is used as a decimal: cos 80° ≈ 0.1736.

    Why does a calculator show −0.1104 for cos 80?

    The calculator is in radian mode (RAD): it takes cos 80 as the cosine of 80 radians, cos 80 rad ≈ −0.1104. Switch it to degrees (DEG): cos 80° ≈ 0.1736. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also