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    Tan 216 Degrees

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

    What is tan 216°?

    Answer

    tan 216° =
    √(5 − 2√5) ≈ 0.7265

    Angle in radians: 216° = 6π/5. The point of the angle is in quadrant III, where tangent is positive.

    ≈ — rounded to 4 decimal places.

    tan 216° = tan(180° + 36°) = tan 36° = √(5 − 2√5)

    tan 216° = sin 216° / cos 216° = (−√(10 − 2√5)/4) / (−(√5 + 1)/4) = √(5 − 2√5)

    Regular pentagon (golden ratio): cos 36° = (√5 + 1)/4.

    tan 36° = sin 36° / cos 36° = √(5 − 2√5)

    xyOP

    P(cos 216°, sin 216°) ≈ (−0.8090, −0.5878)

    T(1, tan 216°) ≈ (1, 0.7265) — where line OP meets the line x = 1, on the extension of the ray beyond O (dashed).

    See Also

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    https://calculat.io/en/number/trigonometry/tan--216Copy
    <a href="https://calculat.io/en/number/trigonometry/tan--216">Tan 216 Degrees: Tangent of 216° on the Unit Circle</a>Copy
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    Tan 216 Degrees: Tangent of 216° on the Unit Circle. tan 216° = √(5 − 2√5) ≈ 0.7265. The tangent is the ratio y/x of the point at 216° on the unit circle; 216° reduces to 36°.
    https://calculat.io/en/number/trigonometry/tan--216/generated.jpgCopy

    FAQ

    What is tan 216°?

    tan 216° = √(5 − 2√5) ≈ 0.7265

    How are sin 36° and cos 54° related?

    They are equal: sin α = cos(90° − α), and 36° + 54° = 90°. So sin 36° = cos 54° = √(10 − 2√5)/4, cos 36° = sin 54° = (√5 + 1)/4, and tan 36° = cot 54° = √(5 − 2√5).

    Why does a calculator show −0.9695 for tan 216?

    The calculator is in radian mode (RAD): it takes tan 216 as the tangent of 216 radians, tan 216 rad ≈ −0.9695. Switch it to degrees (DEG): tan 216° = √(5 − 2√5) ≈ 0.7265. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.