Cot 288 Degrees
Sin, Cos, Tan, Cot of an Angle
What is cot 288°?
Answer
cot 288° =
−√(25 − 10√5)/5 ≈ −0.3249
Angle in radians: 288° = 8π/5. The point of the angle is in quadrant IV, where cotangent is negative.
≈ — rounded to 4 decimal places.
cot 288° = cot(360° − 72°) = −cot 72° = −√(25 − 10√5)/5
cot 288° = cos 288° / sin 288° = ((√5 − 1)/4) / (−√(10 + 2√5)/4) = −√(25 − 10√5)/5
Regular pentagon (golden ratio): cos 36° = (√5 + 1)/4.
cot 72° = tan 18° = sin 18° / cos 18° = √(25 − 10√5)/5
P(cos 288°, sin 288°) ≈ (0.3090, −0.9511)
C(cot 288°, 1) ≈ (−0.3249, 1) — where line OP meets the line y = 1, on the extension of the ray beyond O (dashed).
| Function | Exact value | Decimal |
|---|---|---|
| sin 288° | −√(10 + 2√5)/4 | ≈ −0.9511 |
| cos 288° | (√5 − 1)/4 | ≈ 0.3090 |
| tan 288° | −√(5 + 2√5) | ≈ −3.0777 |
| cot 288° | −√(25 − 10√5)/5 | ≈ −0.3249 |
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See Also
- Arcsin, Arccos, Arctan, Arccot - The angle from the value of its sine, cosine, tangent or cotangent: exact in degrees and π, with the check and the unit circle
- Square Root Calculator - Calculate the square root of any number
- Simplify Square Root Calculator - Write any square root in simplest radical form, step by step
- Geometry Formulas: Area, Volume, Perimeter - The formula for every standard shape, where it comes from, and worked examples
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