Cos 101 Degrees

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

What is cos 101°?

Answer

cos 101° ≈
−0.1908

Angle in radians: 101° = 101π/180. The point of the angle is in quadrant II, where cosine is negative.

≈ — rounded to 4 decimal places. cos 101° can't be written with square roots: 101° is not a multiple of 3°.

cos 101° = cos(180° − 79°) = −cos 79° ≈ −0.1908

P(cos 101°, sin 101°) ≈ (−0.1908, 0.9816)

xyOP

P(cos 101°, sin 101°) ≈ (−0.1908, 0.9816)

Highlighted: the projection on the x-axis — cosine, x ≈ −0.1908.

All four functions of 101°
FunctionExact valueDecimal
sin 101°—≈ 0.9816
cos 101°—≈ −0.1908
tan 101°—≈ −5.1446
cot 101°—≈ −0.1944

Reference angle: cos 79° ≈ 0.1908

See Also

FAQ

What is cos 101°?

cos 101° ≈ −0.1908

Why does cos 101° 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°. 101° is not, so no such exact form exists; the value is used as a decimal: cos 101° ≈ −0.1908.

Why does a calculator show 0.8920 for cos 101?

The calculator is in radian mode (RAD): it takes cos 101 as the cosine of 101 radians, cos 101 rad ≈ 0.8920. Switch it to degrees (DEG): cos 101° ≈ −0.1908. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.