Cartesian Equation to Polar Calculator

Change rectangular equations into polar expressions with guided steps. Compare results, examples, exports, and evaluations. Use clear substitutions for faster coordinate equation review today.

Calculator

Use x, y, ^2, +, -, decimals, and equals signs. Example: x^2 + y^2 + 2x - 4 = 0

Example Data Table

Cartesian equation Polar substitution Simplified polar idea
x^2 + y^2 = 25r^2 cos^2θ + r^2 sin^2θ = 25r = 5
x = 4r cosθ = 4r = 4 secθ
y = 3r sinθ = 3r = 3 cscθ
y = 2xr sinθ = 2r cosθtanθ = 2
x^2 + y^2 + 2x - 4 = 0r^2 + 2r cosθ - 4 = 0Use quadratic formula in r
y^2 = 4xr^2 sin^2θ = 4r cosθr = 4 cosθ / sin^2θ

Formula Used

The calculator uses the coordinate identities x = r cosθ and y = r sinθ.

It also uses x2 + y2 = r2.

For Ax2 + Bxy + Cy2 + Dx + Ey + F = 0, the polar form is:

r2(A cos2θ + B sinθ cosθ + C sin2θ) + r(D cosθ + E sinθ) + F = 0.

When q(θ)r2 + l(θ)r + F = 0, the radius can be solved with the quadratic formula.

How to Use This Calculator

  1. Enter the Cartesian equation in the input box.
  2. Use x and y as coordinate variables.
  3. Enter an angle if you want a numerical radius.
  4. Choose degrees or radians.
  5. Select the root branch and decimal precision.
  6. Press the convert button.
  7. Review the result above the form.
  8. Download the CSV or PDF when needed.

Understanding Cartesian to Polar Conversion

A Cartesian equation uses x and y coordinates. A polar equation uses r and theta. This calculator changes one form into the other. It replaces x with r cos theta. It replaces y with r sin theta. Then it organizes the expression.

The tool is useful for circles, lines, parabolas, and general conics. It can read expanded quadratic equations. These include x squared, xy, y squared, x, y, and constant terms. When that structure is found, the calculator builds a clean polar equation. It also evaluates r for a selected angle.

Why Polar Form Helps

Many curves look simpler in polar form. A circle centered at the origin becomes r equals a constant. A vertical line becomes r cos theta equals a constant. A horizontal line becomes r sin theta equals a constant. Some conics also become easier to inspect.

The result area shows the original equation first. Next, it shows the direct substitution. Then it shows the standard polar structure. For a quadratic equation, the form is q(theta) r squared plus l(theta) r plus f equals zero. This makes the calculation easier to check.

Numerical Angle Evaluation

The angle evaluation is optional. Enter theta in degrees or radians. The calculator computes possible real radius values. It can show the plus root, minus root, or both roots. If the discriminant is negative, no real radius exists for that angle.

Validation helps reduce algebra mistakes. After finding r, the tool computes x and y from the selected angle. It can also show a residual for supported equations. A residual near zero means the converted point fits the original curve.

Exports and Input Tips

The CSV export is helpful for worksheets. The PDF export is useful for reports. Both downloads include the equation, substitution, polar form, angle, and computed values.

Use expanded equations for the strongest results. Avoid hidden multiplication when possible. Write 3*x instead of 3x if you prefer clarity. The parser also understands common compact forms like 3x and x^2. For equations with functions or parentheses, use the direct substitution result. Then simplify the algebra manually if needed. This method keeps the conversion transparent. It also shows every important replacement step.

It supports quick study and classroom checks. It also helps engineering notes and future review tasks.

FAQs

What does this calculator convert?

It converts Cartesian equations with x and y into polar form with r and θ. It also evaluates radius values for supported polynomial equations.

Which substitutions are used?

The calculator uses x = r cosθ and y = r sinθ. It also uses x squared plus y squared equals r squared.

Can it solve every equation for r?

No. It solves supported linear and quadratic expanded equations. Other equations still get direct polar substitution for manual simplification.

Why do I see two radius answers?

A quadratic polar equation can have two real roots. Each root may describe a valid point at the selected angle.

What does residual mean?

Residual is the equation error after putting the computed point back into the original equation. A value near zero is best.

Should I use degrees or radians?

Use the unit that matches your angle value. Degrees are common in classrooms. Radians are common in calculus and advanced graphing.

Can I export the result?

Yes. After calculation, use the CSV or PDF button. The exports include formulas, angle data, and computed radius values.

What input format works best?

Expanded forms work best. Use terms like x^2, xy, y^2, x, y, and constants. Avoid parentheses for automatic solving.

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