Sin 140 Degrees

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

What is sin 140°?

Answer

sin 140° ≈
0.6428

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

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

sin 140° = sin(180° − 40°) = sin 40° ≈ 0.6428

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

xyOP

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

Highlighted: the projection on the y-axis — sine, y ≈ 0.6428.

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: sin 40° ≈ 0.6428

See Also

Recalculate with different values ↑

Sine of nearby angles

Anglesin
130°≈ 0.7660
134°≈ 0.7193
135°√2/2
140°≈ 0.6428
142°≈ 0.6157
144°√(10 − 2√5)/4
145°≈ 0.5736

FAQ

What is sin 140°?

sin 140° ≈ 0.6428

Why does sin 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: sin 140° ≈ 0.6428.

Why does a calculator show 0.9802 for sin 140?

The calculator is in radian mode (RAD): it takes sin 140 as the sine of 140 radians, sin 140 rad ≈ 0.9802. Switch it to degrees (DEG): sin 140° ≈ 0.6428. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

See Also