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    Tan 90 Degrees

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

    What is tan 90°?

    Answer

    tan 90°
    is undefined

    Angle in radians: 90° = π/2. The point of the angle is on the y-axis: (0, 1).

    cos 90° = 0, and tan = sin / cos: you can't divide by zero, so the value doesn't exist.

    tan 90° = sin 90° / cos 90° = 1 / 0

    xyOP

    P(cos 90°, sin 90°) = (0, 1)

    Line OP of 90° runs parallel to the line x = 1: they never meet, so tan 90° doesn't exist.

    All four functions of 90°
    FunctionExact valueDecimal
    sin 90°11
    cos 90°00
    tan 90°undefined—
    cot 90°00

    See Also

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    https://calculat.io/en/number/trigonometry/tan--90Copy
    <a href="https://calculat.io/en/number/trigonometry/tan--90">Tan 90 Degrees: Tangent of 90° on the Unit Circle</a>Copy
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    Tan 90 Degrees: Tangent of 90° on the Unit Circle. tan 90° is undefined: cos 90° = 0, and tan = sin / cos — division by zero. Why, on the unit circle.
    https://calculat.io/en/number/trigonometry/tan--90/generated.jpgCopy

    Tangent of nearby angles

    Angletan
    87°≈ 19.0811
    88°≈ 28.6363
    89°≈ 57.2900
    90°undefined
    97°≈ −8.1443
    98°≈ −7.1154
    100°≈ −5.6713
    Recalculate with different values ↑

    FAQ

    What is tan 90°?

    tan 90° is undefined

    Why does tan 90° not exist?

    The point of 90° on the unit circle is (0, 1): cos 90° = 0, and tan = sin / cos would divide by zero. On the unit circle line OP runs parallel to the line x = 1 and never meets it.

    Why does a calculator show −1.9952 for tan 90?

    The calculator is in radian mode (RAD): it takes tan 90 as the tangent of 90 radians, tan 90 rad ≈ −1.9952. Switch it to degrees (DEG): tan 90° is undefined. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also