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    Cos 159 Degrees

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

    What is cos 159°?

    Answer

    cos 159° ≈
    −0.9336

    Angle in radians: 159° = 53π/60. The point of the angle is in quadrant II, where cosine is negative.

    ≈ — rounded to 4 decimal places. An exact form of cos 159° in square roots exists, but it is unwieldy — nested radicals.

    cos 159° = cos(180° − 21°) = −cos 21° ≈ −0.9336

    P(cos 159°, sin 159°) ≈ (−0.9336, 0.3584)

    xyOP

    P(cos 159°, sin 159°) ≈ (−0.9336, 0.3584)

    Highlighted: the projection on the x-axis — cosine, x ≈ −0.9336.

    All four functions of 159°
    FunctionExact valueDecimal
    sin 159°—≈ 0.3584
    cos 159°—≈ −0.9336
    tan 159°—≈ −0.3839
    cot 159°—≈ −2.6051

    Reference angle: cos 21° ≈ 0.9336

    See Also

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    https://calculat.io/en/number/trigonometry/cos--159Copy
    <a href="https://calculat.io/en/number/trigonometry/cos--159">Cos 159 Degrees: Cosine of 159° on the Unit Circle</a>Copy
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    Cos 159 Degrees: Cosine of 159° on the Unit Circle. cos 159° ≈ −0.9336. The cosine is the x-coordinate of the point at 159° on the unit circle; 159° reduces to 21°.
    https://calculat.io/en/number/trigonometry/cos--159/generated.jpgCopy

    Cosine of nearby angles

    Anglecos
    144°−(√5 + 1)/4
    145°≈ −0.8192
    150°−√3/2
    159°≈ −0.9336
    160°≈ −0.9397
    162°−√(10 + 2√5)/4
    164°≈ −0.9613
    Recalculate with different values ↑

    FAQ

    What is cos 159°?

    cos 159° ≈ −0.9336

    Is there an exact value of cos 159°?

    Yes: 159° is a multiple of 3°, and the values of such angles can be written with square roots — but the expression is unwieldy, with nested radicals built from the values of 18° and 15° (3° = 18° − 15°). In practice the decimal is used: cos 159° ≈ −0.9336.

    Why does a calculator show −0.3425 for cos 159?

    The calculator is in radian mode (RAD): it takes cos 159 as the cosine of 159 radians, cos 159 rad ≈ −0.3425. Switch it to degrees (DEG): cos 159° ≈ −0.9336. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also