Cos 48 Degrees

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

What is cos 48°?

Answer

cos 48° ≈
0.6691

Angle in radians: 48° = 4π/15. The point of the angle is in quadrant I, where cosine is positive.

≈ — rounded to 4 decimal places. An exact form of cos 48° in square roots exists, but it is unwieldy — nested radicals.

P(cos 48°, sin 48°) ≈ (0.6691, 0.7431)

xyOP

P(cos 48°, sin 48°) ≈ (0.6691, 0.7431)

Highlighted: the projection on the x-axis — cosine, x ≈ 0.6691.

All four functions of 48°
FunctionExact valueDecimal
sin 48°—≈ 0.7431
cos 48°—≈ 0.6691
tan 48°—≈ 1.1106
cot 48°—≈ 0.9004

See Also

FAQ

What is cos 48°?

cos 48° ≈ 0.6691

Is there an exact value of cos 48°?

Yes: 48° is a multiple of 3°, and the values of such angles can be written with square roots — but the expression is unwieldy, with nested radicals built from the values of 18° and 15° (3° = 18° − 15°). In practice the decimal is used: cos 48° ≈ 0.6691.

Why does a calculator show −0.6401 for cos 48?

The calculator is in radian mode (RAD): it takes cos 48 as the cosine of 48 radians, cos 48 rad ≈ −0.6401. Switch it to degrees (DEG): cos 48° ≈ 0.6691. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.