Cos 38 Degrees

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

What is cos 38°?

Answer

cos 38° ≈
0.7880

Angle in radians: 38° = 19π/90. The point of the angle is in quadrant I, where cosine is positive.

≈ — rounded to 4 decimal places. cos 38° can't be written with square roots: 38° is not a multiple of 3°.

P(cos 38°, sin 38°) ≈ (0.7880, 0.6157)

xyOP

P(cos 38°, sin 38°) ≈ (0.7880, 0.6157)

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

All four functions of 38°
FunctionExact valueDecimal
sin 38°—≈ 0.6157
cos 38°—≈ 0.7880
tan 38°—≈ 0.7813
cot 38°—≈ 1.2799

See Also

FAQ

What is cos 38°?

cos 38° ≈ 0.7880

Why does cos 38° 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°. 38° is not, so no such exact form exists; the value is used as a decimal: cos 38° ≈ 0.7880.

Why does a calculator show 0.9551 for cos 38?

The calculator is in radian mode (RAD): it takes cos 38 as the cosine of 38 radians, cos 38 rad ≈ 0.9551. Switch it to degrees (DEG): cos 38° ≈ 0.7880. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.