Cos13

Cos13 can refer to the cosine of the real number 13. In standard mathematical practice, the argument of trigonometric functions is given in radians unless otherwise indicated. Therefore cos13 usually means cos(13 radians). Because the cosine function is periodic with period 2π, cos(13) equals cos(13 − 4π) = cos(0.4336...), and its numerical value is approximately 0.907447.

If instead the intention is the cosine of thirteen degrees, written as cos 13°, the value is about 0.97437. The two quantities differ because they measure the angle in different units.

In computing, most programming languages’ standard libraries treat inputs to the cosine function as radians. To compute the cosine of an angle in degrees, one must convert to radians first, for example by multiplying by π/180. Thus cos(13°) = cos(13 × π/180) ≈ cos(0.2269) ≈ 0.97437.

If encountered as a term in datasets or software, cos13 may also appear as a label or identifier, in which case its meaning depends on the surrounding context rather than a mathematical value. In summary, cos13 most commonly denotes a radians-based cosine value near 0.907447, while cos 13° denotes a degree-based value near 0.97437.