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    Cos 125 Degrees

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

    What is cos 125°?

    Answer

    cos 125° ≈
    −0.5736

    Angle in radians: 125° = 25π/36. The point of the angle is in quadrant II, where cosine is negative.

    ≈ — rounded to 4 decimal places. cos 125° can't be written with square roots: 125° is not a multiple of 3°.

    cos 125° = cos(180° − 55°) = −cos 55° ≈ −0.5736

    P(cos 125°, sin 125°) ≈ (−0.5736, 0.8192)

    xyOP

    P(cos 125°, sin 125°) ≈ (−0.5736, 0.8192)

    Highlighted: the projection on the x-axis — cosine, x ≈ −0.5736.

    All four functions of 125°
    FunctionExact valueDecimal
    sin 125°—≈ 0.8192
    cos 125°—≈ −0.5736
    tan 125°—≈ −1.4281
    cot 125°—≈ −0.7002

    Reference angle: cos 55° ≈ 0.5736

    See Also

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    https://calculat.io/en/number/trigonometry/cos--125Copy
    <a href="https://calculat.io/en/number/trigonometry/cos--125">Cos 125 Degrees: Cosine of 125° on the Unit Circle</a>Copy
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    Cos 125 Degrees: Cosine of 125° on the Unit Circle. cos 125° ≈ −0.5736. The cosine is the x-coordinate of the point at 125° on the unit circle; 125° reduces to 55°.
    https://calculat.io/en/number/trigonometry/cos--125/generated.jpgCopy

    Cosine of nearby angles

    Anglecos
    108°−(√5 − 1)/4
    110°≈ −0.3420
    120°−1/2
    125°≈ −0.5736
    126°−√(10 − 2√5)/4
    127°≈ −0.6018
    130°≈ −0.6428
    Recalculate with different values ↑

    FAQ

    What is cos 125°?

    cos 125° ≈ −0.5736

    Why does cos 125° 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°. 125° is not, so no such exact form exists; the value is used as a decimal: cos 125° ≈ −0.5736.

    Why does a calculator show 0.7877 for cos 125?

    The calculator is in radian mode (RAD): it takes cos 125 as the cosine of 125 radians, cos 125 rad ≈ 0.7877. Switch it to degrees (DEG): cos 125° ≈ −0.5736. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also