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    Cos 140 Degrees

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

    What is cos 140°?

    Answer

    cos 140° ≈
    −0.7660

    Angle in radians: 140° = 7π/9. The point of the angle is in quadrant II, where cosine is negative.

    ≈ — rounded to 4 decimal places. cos 140° can't be written with square roots: 140° is not a multiple of 3°.

    cos 140° = cos(180° − 40°) = −cos 40° ≈ −0.7660

    P(cos 140°, sin 140°) ≈ (−0.7660, 0.6428)

    xyOP

    P(cos 140°, sin 140°) ≈ (−0.7660, 0.6428)

    Highlighted: the projection on the x-axis — cosine, x ≈ −0.7660.

    All four functions of 140°
    FunctionExact valueDecimal
    sin 140°—≈ 0.6428
    cos 140°—≈ −0.7660
    tan 140°—≈ −0.8391
    cot 140°—≈ −1.1918

    Reference angle: cos 40° ≈ 0.7660

    See Also

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    https://calculat.io/en/number/trigonometry/cos--140Copy
    <a href="https://calculat.io/en/number/trigonometry/cos--140">Cos 140 Degrees: Cosine of 140° on the Unit Circle</a>Copy
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    Cos 140 Degrees: Cosine of 140° on the Unit Circle. cos 140° ≈ −0.7660. The cosine is the x-coordinate of the point at 140° on the unit circle; 140° reduces to 40°.
    https://calculat.io/en/number/trigonometry/cos--140/generated.jpgCopy

    Cosine of nearby angles

    Anglecos
    130°≈ −0.6428
    134°≈ −0.6947
    135°−√2/2
    140°≈ −0.7660
    142°≈ −0.7880
    144°−(√5 + 1)/4
    145°≈ −0.8192
    Recalculate with different values ↑

    FAQ

    What is cos 140°?

    cos 140° ≈ −0.7660

    Why does cos 140° 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°. 140° is not, so no such exact form exists; the value is used as a decimal: cos 140° ≈ −0.7660.

    Why does a calculator show −0.1978 for cos 140?

    The calculator is in radian mode (RAD): it takes cos 140 as the cosine of 140 radians, cos 140 rad ≈ −0.1978. Switch it to degrees (DEG): cos 140° ≈ −0.7660. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also