Cos 80 Degrees
Sin, Cos, Tan, Cot of an Angle
What is cos 80°?
Answer
cos 80° ≈
0.1736
Angle in radians: 80° = 4π/9. The point of the angle is in quadrant I, where cosine is positive.
≈ — rounded to 4 decimal places. cos 80° can't be written with square roots: 80° is not a multiple of 3°.
P(cos 80°, sin 80°) ≈ (0.1736, 0.9848)
P(cos 80°, sin 80°) ≈ (0.1736, 0.9848)
Highlighted: the projection on the x-axis — cosine, x ≈ 0.1736.
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
Cosine of nearby angles
FAQ
What is cos 80°?
cos 80° ≈ 0.1736
Why does cos 80° have no exact value?
A trigonometric value of a whole number of degrees can be written with square roots only when the angle is a multiple of 3°. 80° is not, so no such exact form exists; the value is used as a decimal: cos 80° ≈ 0.1736.
Why does a calculator show −0.1104 for cos 80?
The calculator is in radian mode (RAD): it takes cos 80 as the cosine of 80 radians, cos 80 rad ≈ −0.1104. Switch it to degrees (DEG): cos 80° ≈ 0.1736. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.
See Also
- Cos 70 Degrees: Cosine of 70° on the Unit Circle
- Cos 71 Degrees: Cosine of 71° on the Unit Circle
- Cos 72 Degrees: Cosine of 72° on the Unit Circle
- Cos 73 Degrees: Cosine of 73° on the Unit Circle
- Cos 74 Degrees: Cosine of 74° on the Unit Circle
- Cos 75 Degrees: Cosine of 75° on the Unit Circle
- Cos 76 Degrees: Cosine of 76° on the Unit Circle
- Cos 77 Degrees: Cosine of 77° on the Unit Circle
- Cos 78 Degrees: Cosine of 78° on the Unit Circle
- Cos 79 Degrees: Cosine of 79° on the Unit Circle
- Cos 81 Degrees: Cosine of 81° on the Unit Circle
- Cos 82 Degrees: Cosine of 82° on the Unit Circle
- Cos 83 Degrees: Cosine of 83° on the Unit Circle
- Cos 84 Degrees: Cosine of 84° on the Unit Circle
- Cos 85 Degrees: Cosine of 85° on the Unit Circle
- Cos 86 Degrees: Cosine of 86° on the Unit Circle
- Cos 87 Degrees: Cosine of 87° on the Unit Circle
- Cos 88 Degrees: Cosine of 88° on the Unit Circle
- Cos 89 Degrees: Cosine of 89° on the Unit Circle
- Cos 90 Degrees: Cosine of 90° on the Unit Circle
- Косинус 80 градусов (cos 80°) на единичной окружности
- Coseno de 80 grados (cos 80°) en el círculo unitario
- Cosseno de 80 graus (cos 80°) no ciclo trigonométrico