Feedback form
Hi! What do you think?

Drag it here or paste with Ctrl+V

    You can also email us on infocalculat.io

    Tan 21 Degrees

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

    What is tan 21°?

    Answer

    tan 21° ≈
    0.3839

    Angle in radians: 21° = 7π/60. The point of the angle is in quadrant I, where tangent is positive.

    ≈ — rounded to 4 decimal places. An exact form of tan 21° in square roots exists, but it is unwieldy — nested radicals.

    tan 21° = sin 21° / cos 21° ≈ 0.3839

    xyOP

    P(cos 21°, sin 21°) ≈ (0.9336, 0.3584)

    T(1, tan 21°) ≈ (1, 0.3839) — where line OP meets the line x = 1.

    All four functions of 21°
    FunctionExact valueDecimal
    sin 21°—≈ 0.3584
    cos 21°—≈ 0.9336
    tan 21°—≈ 0.3839
    cot 21°—≈ 2.6051

    See Also

    Share This Calculation
    Print
    https://calculat.io/en/number/trigonometry/tan--21Copy
    <a href="https://calculat.io/en/number/trigonometry/tan--21">Tan 21 Degrees: Tangent of 21° on the Unit Circle</a>Copy
    Facebook
    Twitter
    Telegram
    WhatsApp
    Viber
    Email
    Tan 21 Degrees: Tangent of 21° on the Unit Circle. tan 21° ≈ 0.3839. The tangent is the ratio y/x of the point at 21° on the unit circle.
    https://calculat.io/en/number/trigonometry/tan--21/generated.jpgCopy

    Tangent of nearby angles

    Angletan
    18°√(25 − 10√5)/5
    19°≈ 0.3443
    20°≈ 0.3640
    21°≈ 0.3839
    22°≈ 0.4040
    23°≈ 0.4245
    24°≈ 0.4452
    Recalculate with different values ↑

    FAQ

    What is tan 21°?

    tan 21° ≈ 0.3839

    Is there an exact value of tan 21°?

    Yes: 21° 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: tan 21° ≈ 0.3839.

    Why does a calculator show −1.5275 for tan 21?

    The calculator is in radian mode (RAD): it takes tan 21 as the tangent of 21 radians, tan 21 rad ≈ −1.5275. Switch it to degrees (DEG): tan 21° ≈ 0.3839. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

    See Also