CAST: which ones are positive
Going round from quadrant I: All are positive, then only Sin, then only Tan, then only Cos. Find the reference angle, use the 0°–90° value, then give it the sign of its quadrant.
Trigonometry Unit Circle ⭕
Drag the point round the circle. sin θ, cos θ and tan θ change on the circle and on their graphs at the same time, with exact values for the special angles.
Drag the angle
Live graphs
Exact values
Nothing leaves your device
- sin θ
- cos θ
- tan θ
Why
The graphs, 0° to 360°
Drag along the graph to move the angle. The height of the sin curve is the red leg on the circle; the cos curve follows the blue leg.
Exact values to learn
Every other special angle uses these five columns, with a + or − sign from its quadrant.
| sin | 0 | 12 | √22 | √32 | 1 |
|---|---|---|---|---|---|
| cos | 1 | √32 | √22 | 12 | 0 |
| tan | 0 | √33 | 1 | √3 | — |
Good to know
Degrees and radians
A full turn is 360° or 2π radians, so 180° = π. To change degrees to radians multiply by π/180; to go back multiply by 180/π.
Nothing leaves your device
Everything is worked out in your browser and nothing is saved. The address bar keeps the numbers, so a link opens the same working.
Tool created by
លោក ណាត ប៊ុនឆ័យ · Mr. Nat Bunchhai
Alpha Academy Cambodia
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