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    Cos 20 Degrees

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

    What is cos 20°?

    Answer

    cos 20° ≈
    0.9397

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

    ≈ — rounded to 4 decimal places. cos 20° can't be written with square roots: 20° is not a multiple of 3°.

    P(cos 20°, sin 20°) ≈ (0.9397, 0.3420)

    xyOP

    P(cos 20°, sin 20°) ≈ (0.9397, 0.3420)

    Highlighted: the projection on the x-axis — cosine, x ≈ 0.9397.

    All four functions of 20°
    FunctionExact valueDecimal
    sin 20°—≈ 0.3420
    cos 20°—≈ 0.9397
    tan 20°—≈ 0.3640
    cot 20°—≈ 2.7475

    See Also

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    https://calculat.io/en/number/trigonometry/cos--20Copy
    <a href="https://calculat.io/en/number/trigonometry/cos--20">Cos 20 Degrees: Cosine of 20° on the Unit Circle</a>Copy
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    Cos 20 Degrees: Cosine of 20° on the Unit Circle. cos 20° ≈ 0.9397. The cosine is the x-coordinate of the point at 20° on the unit circle.
    https://calculat.io/en/number/trigonometry/cos--20/generated.jpgCopy

    Cosine of nearby angles

    Anglecos
    17°≈ 0.9563
    18°√(10 + 2√5)/4
    19°≈ 0.9455
    20°≈ 0.9397
    21°≈ 0.9336
    22°≈ 0.9272
    23°≈ 0.9205
    Recalculate with different values ↑

    FAQ

    What is cos 20°?

    cos 20° ≈ 0.9397

    Why does cos 20° 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°. 20° is not, so no such exact form exists; the value is used as a decimal: cos 20° ≈ 0.9397.

    Why does a calculator show 0.4081 for cos 20?

    The calculator is in radian mode (RAD): it takes cos 20 as the cosine of 20 radians, cos 20 rad ≈ 0.4081. Switch it to degrees (DEG): cos 20° ≈ 0.9397. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also