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    Cos 64 Degrees

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

    What is cos 64°?

    Answer

    cos 64° ≈
    0.4384

    Angle in radians: 64° = 16π/45. The point of the angle is in quadrant I, where cosine is positive.

    ≈ — rounded to 4 decimal places. cos 64° can't be written with square roots: 64° is not a multiple of 3°.

    P(cos 64°, sin 64°) ≈ (0.4384, 0.8988)

    xyOP

    P(cos 64°, sin 64°) ≈ (0.4384, 0.8988)

    Highlighted: the projection on the x-axis — cosine, x ≈ 0.4384.

    All four functions of 64°
    FunctionExact valueDecimal
    sin 64°—≈ 0.8988
    cos 64°—≈ 0.4384
    tan 64°—≈ 2.0503
    cot 64°—≈ 0.4877

    See Also

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    https://calculat.io/en/number/trigonometry/cos--64Copy
    <a href="https://calculat.io/en/number/trigonometry/cos--64">Cos 64 Degrees: Cosine of 64° on the Unit Circle</a>Copy
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    Cos 64 Degrees: Cosine of 64° on the Unit Circle. cos 64° ≈ 0.4384. The cosine is the x-coordinate of the point at 64° on the unit circle.
    https://calculat.io/en/number/trigonometry/cos--64/generated.jpgCopy

    Cosine of nearby angles

    Anglecos
    61°≈ 0.4848
    62°≈ 0.4695
    63°≈ 0.4540
    64°≈ 0.4384
    65°≈ 0.4226
    66°≈ 0.4067
    67°≈ 0.3907
    Recalculate with different values ↑

    FAQ

    What is cos 64°?

    cos 64° ≈ 0.4384

    Why does cos 64° 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°. 64° is not, so no such exact form exists; the value is used as a decimal: cos 64° ≈ 0.4384.

    Why does a calculator show 0.3919 for cos 64?

    The calculator is in radian mode (RAD): it takes cos 64 as the cosine of 64 radians, cos 64 rad ≈ 0.3919. Switch it to degrees (DEG): cos 64° ≈ 0.4384. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also