Cot 21 Degrees

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

What is cot 21°?

Answer

cot 21° ≈
2.6051

Angle in radians: 21° = 7π/60. The point of the angle is in quadrant I, where cotangent is positive.

≈ — rounded to 4 decimal places. An exact form of cot 21° in square roots exists, but it is unwieldy — nested radicals.

cot 21° = cos 21° / sin 21° ≈ 2.6051

xyOP

P(cos 21°, sin 21°) ≈ (0.9336, 0.3584)

C(cot 21°, 1) ≈ (2.6051, 1) — where line OP meets the line y = 1; C is beyond the drawing, the arrow points to it.

All four functions of 21°
FunctionExact valueDecimal
sin 21°—≈ 0.3584
cos 21°—≈ 0.9336
tan 21°—≈ 0.3839
cot 21°—≈ 2.6051

See Also

Recalculate with different values ↑

Cotangent of nearby angles

Anglecot
18°√(5 + 2√5)
19°≈ 2.9042
20°≈ 2.7475
21°≈ 2.6051
22°≈ 2.4751
23°≈ 2.3559
24°≈ 2.2460

FAQ

What is cot 21°?

cot 21° ≈ 2.6051

Is there an exact value of cot 21°?

Yes: 21° 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: cot 21° ≈ 2.6051.

Why does a calculator show −0.6547 for cot 21?

The calculator is in radian mode (RAD): it takes cot 21 as the cotangent of 21 radians, cot 21 rad ≈ −0.6547. Switch it to degrees (DEG): cot 21° ≈ 2.6051. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

See Also