Cos 27 Degrees

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

What is cos 27°?

Answer

cos 27° ≈
0.8910

Angle in radians: 27° = 3π/20. The point of the angle is in quadrant I, where cosine is positive.

≈ — rounded to 4 decimal places. An exact form of cos 27° in square roots exists, but it is unwieldy — nested radicals.

P(cos 27°, sin 27°) ≈ (0.8910, 0.4540)

xyOP

P(cos 27°, sin 27°) ≈ (0.8910, 0.4540)

Highlighted: the projection on the x-axis — cosine, x ≈ 0.8910.

All four functions of 27°
FunctionExact valueDecimal
sin 27°—≈ 0.4540
cos 27°—≈ 0.8910
tan 27°—≈ 0.5095
cot 27°—≈ 1.9626

See Also

Recalculate with different values ↑

Cosine of nearby angles

Anglecos
24°≈ 0.9135
25°≈ 0.9063
26°≈ 0.8988
27°≈ 0.8910
28°≈ 0.8829
29°≈ 0.8746
30°√3/2

FAQ

What is cos 27°?

cos 27° ≈ 0.8910

Is there an exact value of cos 27°?

Yes: 27° 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: cos 27° ≈ 0.8910.

Why does a calculator show −0.2921 for cos 27?

The calculator is in radian mode (RAD): it takes cos 27 as the cosine of 27 radians, cos 27 rad ≈ −0.2921. Switch it to degrees (DEG): cos 27° ≈ 0.8910. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

See Also