Cot 78 Degrees

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

What is cot 78°?

Answer

cot 78° ≈
0.2126

Angle in radians: 78° = 13π/30. The point of the angle is in quadrant I, where cotangent is positive.

≈ — rounded to 4 decimal places. An exact form of cot 78° in square roots exists, but it is unwieldy — nested radicals.

cot 78° = cos 78° / sin 78° ≈ 0.2126

xyOP

P(cos 78°, sin 78°) ≈ (0.2079, 0.9781)

C(cot 78°, 1) ≈ (0.2126, 1) — where line OP meets the line y = 1.

All four functions of 78°
FunctionExact valueDecimal
sin 78°—≈ 0.9781
cos 78°—≈ 0.2079
tan 78°—≈ 4.7046
cot 78°—≈ 0.2126

See Also

Recalculate with different values ↑

Cotangent of nearby angles

Anglecot
75°2 − √3
76°≈ 0.2493
77°≈ 0.2309
78°≈ 0.2126
79°≈ 0.1944
80°≈ 0.1763
81°≈ 0.1584

FAQ

What is cot 78°?

cot 78° ≈ 0.2126

Is there an exact value of cot 78°?

Yes: 78° 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 78° ≈ 0.2126.

Why does a calculator show −1.6689 for cot 78?

The calculator is in radian mode (RAD): it takes cot 78 as the cotangent of 78 radians, cot 78 rad ≈ −1.6689. Switch it to degrees (DEG): cot 78° ≈ 0.2126. In radians the value is never undefined: π is irrational, so a whole number of radians never lands exactly on an axis.

See Also