Cos 40 Degrees
Sin, Cos, Tan, Cot of an Angle
What is cos 40°?
Answer
cos 40° ≈
0.7660
Angle in radians: 40° = 2π/9. The point of the angle is in quadrant I, where cosine is positive.
≈ — rounded to 4 decimal places. cos 40° can't be written with square roots: 40° is not a multiple of 3°.
P(cos 40°, sin 40°) ≈ (0.7660, 0.6428)
P(cos 40°, sin 40°) ≈ (0.7660, 0.6428)
Highlighted: the projection on the x-axis — cosine, x ≈ 0.7660.
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 40°?
cos 40° ≈ 0.7660
Why does cos 40° 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°. 40° is not, so no such exact form exists; the value is used as a decimal: cos 40° ≈ 0.7660.
Why does a calculator show −0.6669 for cos 40?
The calculator is in radian mode (RAD): it takes cos 40 as the cosine of 40 radians, cos 40 rad ≈ −0.6669. Switch it to degrees (DEG): cos 40° ≈ 0.7660. 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 30 Degrees: Cosine of 30° on the Unit Circle
- Cos 31 Degrees: Cosine of 31° on the Unit Circle
- Cos 32 Degrees: Cosine of 32° on the Unit Circle
- Cos 33 Degrees: Cosine of 33° on the Unit Circle
- Cos 34 Degrees: Cosine of 34° on the Unit Circle
- Cos 35 Degrees: Cosine of 35° on the Unit Circle
- Cos 36 Degrees: Cosine of 36° on the Unit Circle
- Cos 37 Degrees: Cosine of 37° on the Unit Circle
- Cos 38 Degrees: Cosine of 38° on the Unit Circle
- Cos 39 Degrees: Cosine of 39° on the Unit Circle
- Cos 41 Degrees: Cosine of 41° on the Unit Circle
- Cos 42 Degrees: Cosine of 42° on the Unit Circle
- Cos 43 Degrees: Cosine of 43° on the Unit Circle
- Cos 44 Degrees: Cosine of 44° on the Unit Circle
- Cos 45 Degrees: Cosine of 45° on the Unit Circle
- Cos 46 Degrees: Cosine of 46° on the Unit Circle
- Cos 47 Degrees: Cosine of 47° on the Unit Circle
- Cos 48 Degrees: Cosine of 48° on the Unit Circle
- Cos 49 Degrees: Cosine of 49° on the Unit Circle
- Cos 50 Degrees: Cosine of 50° on the Unit Circle
- Косинус 40 градусов (cos 40°) на единичной окружности
- Coseno de 40 grados (cos 40°) en el círculo unitario
- Cosseno de 40 graus (cos 40°) no ciclo trigonométrico