Tan 140 Degrees

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

What is tan 140°?

Answer

tan 140° ≈
−0.8391

Angle in radians: 140° = 7π/9. The point of the angle is in quadrant II, where tangent is negative.

≈ — rounded to 4 decimal places. tan 140° can't be written with square roots: 140° is not a multiple of 3°.

tan 140° = tan(180° − 40°) = −tan 40° ≈ −0.8391

tan 140° = sin 140° / cos 140° ≈ −0.8391

xyOP

P(cos 140°, sin 140°) ≈ (−0.7660, 0.6428)

T(1, tan 140°) ≈ (1, −0.8391) — where line OP meets the line x = 1, on the extension of the ray beyond O (dashed).

All four functions of 140°
FunctionExact valueDecimal
sin 140°—≈ 0.6428
cos 140°—≈ −0.7660
tan 140°—≈ −0.8391
cot 140°—≈ −1.1918

Reference angle: tan 40° ≈ 0.8391

See Also

Recalculate with different values ↑

Tangent of nearby angles

Angletan
130°≈ −1.1918
134°≈ −1.0355
135°−1
140°≈ −0.8391
142°≈ −0.7813
144°−√(5 − 2√5)
145°≈ −0.7002

FAQ

What is tan 140°?

tan 140° ≈ −0.8391

Why does tan 140° 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°. 140° is not, so no such exact form exists; the value is used as a decimal: tan 140° ≈ −0.8391.

Why does a calculator show −4.9554 for tan 140?

The calculator is in radian mode (RAD): it takes tan 140 as the tangent of 140 radians, tan 140 rad ≈ −4.9554. Switch it to degrees (DEG): tan 140° ≈ −0.8391. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

See Also