Unit Circle Calculator
One angle. The complete circle.
Explore an angle
Locate its terminal point and all six trig values.
Use signed finite decimals, scientific e notation or fractions of integers. Complete turns are reduced before numerical evaluation.
Changes how the retained number is interpreted. All normalized output conventions are shown together.
Explore and compare
Loads the selected angle in degrees, with exact values at fifteen-degree intervals.
Keyboard arrows change one degree. Moving this slider switches the source convention to degrees.
Exact radicals stay unchanged. Nonzero values below the chosen decimal scale retain scientific notation.
Finite inputs support forty significant digits per number. Nonzero source magnitudes range from through . Ordinary decimal radians are capped at in magnitude to control numerical range reduction. Exact angular reductions precede trigonometry; general trig values have double-precision numerical limits.
Interpreted source angle
Terminal point
Quadrant I. Signs follow the actual terminal point.
Angle relationships
Exact angle relationships are separate from rounded radian views. Near a boundary, a rounded label can coincide with the axis value without changing the actual location.
- Normalized angle in degrees
- Exact relationship
- Normalized angle in pi radians
- Exact relationship
- Normalized angle in ordinary radians
- Numerical view
- Normalized angle in turns
- Exact relationship
- Reference angle in degrees
- Exact relationship
- One additional positive coterminal angle
- Exact relationship
- One negative coterminal angle
- Exact relationship
All six trigonometric functions
| Function | Exact value or domain | Rounded decimal |
|---|---|---|
| Sine | ||
| Cosine | ||
| Tangent | ||
| Cosecant | ||
| Secant | ||
| Cotangent |
Decimal precision changes the rounded view, never the domain or the exact expression. Nonzero tiny values use scientific notation. General-angle values are numerical approximations, even when a rounded decimal looks like an integer.
Step-by-step solution
1. Interpret the supplied angle
The source convention controls the meaning of the retained input. A symbolic pi radian expression retains its exact coefficient.
2. Remove complete rotations
Use a floor quotient, including for negative sources, to leave a terminal position in one counterclockwise revolution. General ordinary-radian conversions are numerical.
3. Identify the quadrant and reference angle
Measure the acute reference angle to the nearest horizontal semiaxis. The terminal point determines the signs of the coordinate ratios.
4. Read the coordinate functions
This reference angle is a multiple of fifteen degrees, so its signed radical values remain exact.
5. Apply ratio definitions only on their domains
Tangent and secant require a nonzero cosine. Cosecant and cotangent require a nonzero sine. No large finite pole estimate is substituted for an exactly undefined ratio.
6. Check the unit radius
The displayed point comes from the same reduced angle as the ratios. Its squared radius checks the circular geometry within floating-point precision; this is not an exact algebraic certificate for general angles.
The reference-angle rule assumes . It is in the first quadrant, in the second, in the third and in the fourth.
Complete special-angle reference
Every fifteen-degree interval in one closed revolution. The final row repeats the starting point after a complete turn. Undefined functions retain their original denominator restrictions.
| Degrees | Radians | Sine | Cosine | Tangent | Cosecant | Secant | Cotangent |
|---|---|---|---|---|---|---|---|
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Connect rotations, coordinates and exact values
Follow the same point through different rotations
Explore clockwise sources, counterclockwise sources and multiple complete turns without confusing angular travel with terminal position. Every source retains its interpretation in the working. Normalized degrees, ordinary radians, pi radians and turns describe the same endpoint together. A separate pair of coterminal examples makes periodicity visible without replacing the angle that was originally entered or silently discarding the signed rotation record.
Build a complete trigonometric comparison
Compare sine and cosine with tangent and all three reciprocal functions at the same position. Each function retains its own denominator restriction. The exact table extends through all four quadrants and includes every fifteen-degree interval. Numerical values sit beside exact certificates where available, allowing a learner to compare signs, magnitudes and approximations without mistaking the rounded display for a proof of an exact relationship.
Create a reusable study record
Combine the literal source, convention, reference angle, terminal point and ratio definitions in one saved calculation. A hidden reference table remains available in CSV. A visible reference table becomes part of the printable record. Sharing preserves the supported input and display choices. These options help a teacher or student revisit the same problem rather than trying to reconstruct an angle from an isolated screenshot of its final decimal values.
Unit-circle formulas and worked examples
At , the reference angle is . The second quadrant gives and . At , cosine is zero, so tangent and secant are undefined while cotangent remains zero.
At , adding one turn gives the normalized angle . Its terminal point is . The negative sine and positive cosine make tangent negative. An ordinary radian source of has no claimed short radical form in this tool and is evaluated numerically.
Read every standard angle from one coordinate rule
A unit-circle point is not a list to memorize in isolation. At an angle , the point is . The first-quadrant magnitudes repeat through the other quadrants, while the x- and y-signs change with the point's location.
Sign pattern by quadrant
Angles start on the positive x-axis and increase counterclockwise. Tangent follows , so its sign comes from the sine and cosine signs.
- Quadrant I
- cosine positive, sine positive, tangent positive.
- Quadrant II
- cosine negative, sine positive, tangent negative.
- Quadrant III
- cosine negative, sine negative, tangent positive.
- Quadrant IV
- cosine positive, sine negative, tangent negative.
- Horizontal axis
- sine is zero, so tangent is zero.
- Vertical axis
- cosine is zero, so tangent is undefined.
Use a reference angle for magnitude
A reference angle is the acute angle between the terminal side and the x-axis. Standard angles such as 30, 45, and 60 degrees provide the same absolute coordinate values in every quadrant.
For 150 degrees, the reference angle is 30 degrees. The magnitude pair is therefore , and quadrant II changes only the x-sign: .
Connect degrees, radians, and turns
A half turn is 180 degrees or , and a quarter turn is 90 degrees or . Adding a full -radian turn returns to the same coordinate.
Use radian labels when working with arc length, calculus, or identities. Use degrees when a diagram or instruction expresses familiar portions of a turn. The coordinate does not depend on which label system names the angle.
Interpret tangent as a ratio
Tangent equals sine divided by cosine, or on the unit circle. At 45 degrees both coordinates have the same nonzero magnitude, so the ratio is 1.
At 90 and 270 degrees, . Division by zero is undefined, which is why the reference table does not show a finite tangent value for the vertical-axis angles.
Worked check: locate 150 degrees
- 1Find the reference angle: .
- 2Start with the 30-degree magnitudes and .
- 3Apply quadrant II signs to get ; tangent is .
Reference boundaries
- The visible table highlights common axis and first-quadrant angles. Apply reference-angle and sign rules for standard angles such as 120, 135, 150, 210, 225, 240, 300, 315, and 330 degrees.
- Exact radicals are preferable in symbolic work. Decimal values can be useful for measurement or software inputs, but their precision depends on the rounding you choose.
- The unit circle defines trigonometric values for angles; it does not by itself solve a triangle. A triangle problem also needs side, angle, and geometry constraints.
Sources and definitions
- NIST SP 330, Section 5: angle units
Reference for degree and radian conventions used in the table and diagram.
Why units, signs and domains remain visible
The mathematical model stays explicit
- The circle has unit radius and equal horizontal and vertical scales.
- Axes are named as boundaries rather than assigned to a neighboring quadrant.
- Exact reduction handles negative and additional rotations before numerical evaluation.
- Undefined functions follow their original sine or cosine denominators.
Approximation is an explained choice
- Exact fifteen-degree reference values retain their signed radicals.
- Ordinary radian decimals are never guessed to be symbolic pi inputs.
- Tiny nonzero numerical values retain a scientific view at low display precision.
- Angle relationships, decimal views and physical drawing resolution are distinguished.
A practical reference for connected trigonometry
Students learning beyond the first quadrant
Start with the familiar positive-coordinate triangle, then move into the other quadrants while keeping the same circle. The reference angle explains the magnitude, and the coordinate signs explain which functions become negative. Compare vertical and horizontal boundaries separately. This approach connects a memorized table to a geometric definition and makes the different domains of tangent and cotangent easier to understand.
Teachers explaining exact and measured angles
Contrast a symbolic pi source with an ordinary decimal radian measurement that is merely close to it. Follow the ordered equations to show why a numerical answer can approach an axis without becoming an exact axis case. Use the fifteen-degree examples to introduce angle-difference identities, then compare a general input whose terminal coordinates require numerical evaluation rather than a short radical expression.
Learners revising circular motion foundations
Use a normalized terminal position to describe direction while retaining complete rotations in the source record. The circle is dimensionless and does not introduce a physical radius, speed or elapsed time. For an applied motion problem, those quantities need an additional model. This page supplies the angular and trigonometric relationships that such a model can build on, together with the assumptions needed to interpret them correctly.
How it works in three quick steps.
Identify the source angle convention
Enter a signed angle in degrees, ordinary radians, multiples of pi radians or turns. Use finite decimals, scientific e notation or integer fractions. In radians mode, pi syntax also accepts expressions such as pi/6 and -2pi/3. Selecting another source convention reinterprets the retained number; the normalized outputs show conversions of the solved angle.
Locate the terminal point and inspect the domains
Read the normalized angle, location and reference angle before inspecting the six function values. The drawing keeps equal horizontal and vertical units. Exact fifteen-degree reference values remain radical expressions, while general numerical values are labelled approximate. At exact axes, the original sine or cosine denominator determines which functions are undefined.
Compare a full revolution and retain the working
Use the special-angle selector or the keyboard-accessible degree slider to explore another terminal position. Review the complete reference table and ordered working. Download CSV with hidden reference rows, copy a readable summary, share all display choices or print the currently visible calculation and table to a PDF through the browser.
Keep the angle, domains and working together
Download a complete CSV
The spreadsheet-friendly record includes both the active calculation and all special-angle reference values. Exact expressions are converted to readable text because a CSV cell cannot render visual LaTeX. Formula-like source cells are protected against spreadsheet execution. The export retains whether a value is exact, numerical or undefined, so the meaning survives after the presentation format changes.
Print a focused mathematical PDF
Choose Print / Save PDF and use the browser's PDF destination. The print layout removes controls and supporting article sections, expands the result to the printable width and keeps visible mathematics available. Enable the diagram, working and reference table before printing if you want them included. Portrait A4 or Letter works for the main calculation; the wide reference uses a compact print presentation.
Share or copy the supported problem
A shareable fragment keeps the source convention, literal angle, precision and visibility switches. Loading a malformed fragment leaves the current problem unchanged and reports the issue. A copied summary includes the same active problem and complete working as readable plain text. If the browser does not offer clipboard access, CSV provides a separate way to keep the calculation without losing its assumptions.
Frequently Asked Questions
What is a unit circle calculator?
Can I enter radians using pi instead of a decimal?
How are negative angles and extra rotations handled?
Which trigonometric values are exact?
Why is tangent undefined at a vertical axis?
Is cotangent always the reciprocal of tangent?
What does the reference angle mean on an axis?
Does increasing decimal precision change the answer?
Why does the diagram sometimes look as if the point is on an axis?
What is included when I save or share a calculation?
Related calculators
A full-circle explanation rather than a first-quadrant lookup
The unit circle is a compact model that joins a geometric direction to functions used throughout trigonometry. Its center is the origin and its radius is , so its coordinates satisfy . Starting on the positive horizontal axis, a signed rotation determines a terminal ray. The intersection of that ray with the circle gives cosine horizontally and sine vertically. This definition continues through every quadrant and complete revolution, where a right-triangle-only picture needs additional sign rules or a carefully chosen reference angle.
This calculator keeps the rotation and terminal position related but distinct. A source of several complete turns has a different angular travel from its normalized counterpart, even though both reach the same point. Exact rational reduction preserves that distinction for degree, turn and symbolic pi-radian sources. Ordinary decimal radians remain numerical measurements; an eighty-four-decimal-place pi constant controls range reduction before double-precision trigonometry is evaluated on a small argument. The interface states the input bounds, approximation status and plotting resolution rather than claiming that all decimal digits are exact.
The six functions do not share one universal domain. Their original coordinate denominators must be checked separately, especially at axes. The reference table and interactive output therefore retain undefined values as domain statements. Every defined fifteen-degree special value has a rational or radical expression; other angles receive a numerical view. The diagram uses the same reduced model as the computed point and keeps both physical axis units equal. Together, the source record, angle relationships, ordered working and export options make the page useful for explanation and revision as well as a quick numerical check.
Who maintains this page
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Written and maintained by the Toolarithm editorial team. No review date is shown without a maintained editorial record. No independent professional review is claimed.
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