Solve exterior angles fast with validation, conversions, and summaries. Review each vertex clearly and compare. Export clean results for homework, checking, sharing, and revision.
Enter three or four values. Leave one field blank to solve the missing angle.
| Vertex | Interior (°) | Exterior (°) | Check |
|---|---|---|---|
| A | 90 | 90 | 180 total at vertex |
| B | 80 | 100 | 180 total at vertex |
| C | 100 | 80 | 180 total at vertex |
| D | 90 | 90 | 180 total at vertex |
| Exterior sum | 360° | ||
For a convex quadrilateral, the four interior angles always add to 360°.
Interior total: A + B + C + D = 360°
Each exterior angle is supplementary to its matching interior angle.
Exterior at a vertex: Exterior = 180° − Interior
The sum of one exterior angle at each vertex is always 360°.
Exterior total: E₁ + E₂ + E₃ + E₄ = 360°
When one angle is missing, subtract the known three-angle total from 360°.
A quadrilateral has four vertices, four interior angles, and four matching exterior angles. When you extend one side at each vertex, the outside angle formed is the exterior angle. In a convex quadrilateral, every exterior angle is positive and each interior and exterior pair adds to 180°.
This calculator helps students, teachers, and exam candidates confirm that angle data is valid. It supports solving one missing value, converting interior angles into exterior angles, and checking whether the complete set follows the standard turning-angle rule. The graph also makes angle comparisons easier.
Exterior angles are useful in polygon geometry because they connect local angle relationships with total turning. If you move around a convex quadrilateral and turn once at every vertex, the total turn is 360°. That idea is why the exterior angle sum remains fixed, even when the shape is stretched or tilted.
Use the calculator during homework checks, worksheet creation, quick revision, or classroom demonstrations. You can enter a full set to verify accuracy or enter three values to solve the fourth. The radians output is also useful when you want a trigonometry-friendly version of the same result.
The sum is always 360° when one exterior angle is taken at each vertex of a convex quadrilateral.
Subtract the interior angle from 180°. The two angles form a straight line, so they are supplementary.
Yes. Enter any three valid angles in the chosen mode and leave one box empty. The calculator solves the missing value automatically.
Every quadrilateral can be divided into two triangles. Since each triangle totals 180°, the quadrilateral totals 360°.
The calculator is designed for convex quadrilaterals. In that case, each interior and exterior angle stays between 0° and 180°.
Exterior spread is the difference between the largest and smallest exterior angles. It shows how uneven the turning angles are.
Radians help when linking geometry results to trigonometry, graphs, and higher-level mathematics work.
Check that you entered at least three angles, left only one blank, and used values that satisfy the required total.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.