Cos 142 Degrees

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

What is cos 142°?

Answer

cos 142° ≈
−0.7880

Angle in radians: 142° = 71π/90. The point of the angle is in quadrant II, where cosine is negative.

≈ — rounded to 4 decimal places. cos 142° can't be written with square roots: 142° is not a multiple of 3°.

cos 142° = cos(180° − 38°) = −cos 38° ≈ −0.7880

P(cos 142°, sin 142°) ≈ (−0.7880, 0.6157)

xyOP

P(cos 142°, sin 142°) ≈ (−0.7880, 0.6157)

Highlighted: the projection on the x-axis — cosine, x ≈ −0.7880.

All four functions of 142°
FunctionExact valueDecimal
sin 142°—≈ 0.6157
cos 142°—≈ −0.7880
tan 142°—≈ −0.7813
cot 142°—≈ −1.2799

Reference angle: cos 38° ≈ 0.7880

See Also

Recalculate with different values ↑

Cosine of nearby angles

Anglecos
134°≈ −0.6947
135°−√2/2
140°≈ −0.7660
142°≈ −0.7880
144°−(√5 + 1)/4
145°≈ −0.8192
150°−√3/2

FAQ

What is cos 142°?

cos 142° ≈ −0.7880

Why does cos 142° 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°. 142° is not, so no such exact form exists; the value is used as a decimal: cos 142° ≈ −0.7880.

Why does a calculator show −0.8090 for cos 142?

The calculator is in radian mode (RAD): it takes cos 142 as the cosine of 142 radians, cos 142 rad ≈ −0.8090. Switch it to degrees (DEG): cos 142° ≈ −0.7880. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

See Also