Trig Calculator
Sine, cosine, tangent from degrees or radians.
What it does
Sine, cosine, and tangent read triangles from angles: opposite and adjacent over hypotenuse with tangent as their ratio. This page returns all three from degrees or radians to three decimals.
The default is 30 degrees. Sine is 0.5, cosine is 0.866, and tangent is 0.577. Forty five degrees gives 0.707 twice with tangent 1, while 90 degrees leaves tangent undefined over zero cosine.
Radians suit calculus and code while degrees suit geometry and tools. Flip the unit switch rather than converting by hand, since pi slips hide in halves and doubles.
Three decimals guide setup, not proofs. Fine work near poles needs more digits or exact roots like half and root two over two.
How to use
- Enter the angle.
- Pick degrees or radians.
- Read sine first.
- Read cosine next.
- Read tangent last.
Formula
- angle
- Angle in degrees or radians.
Degrees convert at pi over 180 inside; radians enter directly. Tangent divides by cosine and reports undefined at poles like 90 degrees. Rounding is to three decimals in the tool.
Worked example
Example: 30 degrees
30 degrees.
- Radians: 30 x pi/180 = 0.5236.
- Sine: sin(0.5236) = 0.5.
- Cosine: cos(0.5236) = 0.866.
- Tangent: 0.5 / 0.866 = 0.577.
- Tool shows 0.5, 0.866, 0.577.
Reference table
| Angle | Sin | Cos | Tan |
|---|---|---|---|
| 0 deg | 0 | 1 | 0 |
| 30 deg | 0.5 | 0.866 | 0.577 |
| 45 deg | 0.707 | 0.707 | 1 |
| 60 deg | 0.866 | 0.5 | 1.732 |
| 90 deg | 1 | 0 | undefined |
Limits
- Three decimals. Fine work needs more.
- Principal values only.
- Poles give undefined tan.
- No inverse functions.
Common mistakes
- Mixing degrees with radians.
- Reading tan at poles as zero.
- Trusting three decimals for proofs.
- Forgetting tan is sin over cos.
- Entering slopes as angles.
Try it yourself
Quick checks. Answers sit tucked under each question.
45 degrees?
0.707, 0.707, 1.
0 degrees?
0, 1, 0.
Questions
Sine of 30 degrees?
0.5 with cos 0.866 and tan 0.577.
45 degrees?
0.707 each with tan 1.
90 degrees?
Sine 1, cosine 0, tangent undefined (over zero).
Radians mode?
Yes. Switch unit to radians for pi based math.
Arcsin included?
No. Inverse functions need their own pass.
Triangle sides?
No. Triangles and slopes use these outputs next.