tan(90°) is undefined.
tan(90°) is undefined. The angle 90° equals π/2 radians (90 × π/180).
Tangent is sine divided by cosine. At 90° the cosine is 0, so the ratio would need division by zero. The graph of tan has a vertical asymptote at this angle and the value grows without limit as you approach it.
90° lies on the positive y-axis. Remember that tangent is positive in quadrants I and III, and negative in the others, which decides the sign of the answer.
If you get a different number, the calculator is probably in RAD mode. In radians you would enter π/2 instead of 90.
| sin 90° | = 1 |
| cos 90° | = 0 |
| tan 90° | = undefined |
| Angle | Radians | Tan |
|---|---|---|
| 0° | 0 | 0 |
| 30° | π/6 | 0.57735 |
| 45° | π/4 | 1 |
| 60° | π/3 | 1.732051 |
| 90° | π/2 | undefined |
| 120° | 2π/3 | -1.732051 |
| 135° | 3π/4 | -1 |
| 150° | 5π/6 | -0.57735 |
| 180° | π | 0 |
| 270° | 3π/2 | undefined |
| 360° | 2π | 0 |
tan(90°) is undefined.
90° = π/2 radians, so tan(90°) = tan(π/2) = undefined.
It is most likely set to radians. Switch to degree (DEG) mode before entering the angle.
Neither: the value is undefined.
Yes. Use the calculator on this page, or open the full free Scientific Calculator with memory, history and keyboard support.