Triangle geometry suite

Triangle Median Calculator

Find every triangle median accurately and quickly. Use sides or coordinates with complete input validation. Review centroid ratios, diagrams, exports, and saved history instantly.

Calculator inputs

Enter three sides or three coordinate points.

cm
Opposite vertex A. Fractions like 7/8 work.
cm
Opposite vertex B. Fractions like 7/8 work.
cm
Opposite vertex C. Fractions like 7/8 work.

Units and formatting

Example: one custom input unit equals 0.5 meters.
Used only when custom output units are selected.

Example triangles

Load a tested example into the side-length form.

Side aSide bSide cTriangle typeAction
345Right scalene
556Acute isosceles
888Equilateral
7912Obtuse scalene
131415Acute scalene

Formula used

A median joins one vertex to the opposite side midpoint. Every triangle always has exactly three medians.

ma = ½√(2b² + 2c² − a²)
mb = ½√(2a² + 2c² − b²)
mc = ½√(2a² + 2b² − c²)

These equations follow from Apollonius’s theorem. Each formula uses all three side lengths.

Heron’s area formula

s = (a + b + c) ÷ 2,   Area = √[s(s − a)(s − b)(s − c)]

The area supports altitude, inradius, and circumradius calculations. Invalid triangles are rejected before these values appear.

How to use this calculator

  1. Choose side-length or coordinate mode.
  2. Enter three sides or three vertex pairs.
  3. Select input and output measurement units.
  4. Choose precision, notation, and rounding settings.
  5. Press the calculation button.
  6. Review medians, centroid divisions, and geometry details.
  7. Export, print, copy, or share the report.

Understanding triangle medians

A triangle median begins at a vertex. It ends at the opposite side midpoint. This construction divides the opposite side into equal segments.

All three medians meet at the centroid. The centroid is the triangle’s balance point. Uniform triangular material balances at this location.

The centroid divides every median predictably. The vertex section occupies two thirds. The midpoint section occupies one third.

Medians, altitudes, and angle bisectors

A median targets the opposite midpoint. An altitude creates a perpendicular segment. An angle bisector divides one vertex angle equally.

These segments may overlap in special triangles. Equilateral triangles make all three constructions identical. Isosceles triangles create one shared symmetry segment.

Why the longest side has the shortest median

The median formula subtracts the opposite side squared. A larger opposite side reduces the median radicand. Therefore, the longest side faces the shortest median.

This inverse relationship helps verify results. It also catches mislabeled side inputs. The summary identifies both extreme median lengths.

Coordinate geometry mode

Coordinate mode first measures all three sides. It then calculates each opposite midpoint. Finally, it forms the three median line equations.

The coordinate centroid uses simple averaging. Its x-coordinate averages all vertex x-values. Its y-coordinate averages all vertex y-values.

Practical uses

Medians support geometric design and structural layout. They help locate balanced attachment points. They also appear in computer graphics and surveying.

Teachers use medians for theorem demonstrations. Students use them for triangle proofs. Designers use centroids when placing labels and shapes.

Frequently asked questions

What is a median of a triangle?

A median is a segment joining a vertex to the midpoint of the opposite side.

How many medians does a triangle have?

Every nondegenerate triangle has exactly three medians, one from each vertex.

Do all triangle medians intersect?

Yes. All three medians meet at one common point called the centroid.

How does the centroid divide each median?

The centroid creates a 2:1 ratio. The vertex-to-centroid part is twice the remaining part.

Can a median also be an altitude?

Yes. This happens along symmetry lines in isosceles and equilateral triangles.

Are all medians equal in an equilateral triangle?

Yes. Equal sides create equal medians, altitudes, and angle bisectors.

Can fractions be entered?

Yes. Inputs such as 7/8, 3/2, and negative coordinate fractions are supported.

Why are invalid side combinations rejected?

Three lengths must satisfy every triangle inequality. Otherwise, no closed triangle exists.

Does coordinate mode find line equations?

Yes. It finds each opposite midpoint and produces every median line equation.

What is an exact median form?

When a suitable integer radicand exists, the calculator simplifies the square root symbolically.

Can I export the calculation?

Yes. CSV, JSON, PDF, printable, copied, shared, and SVG diagram exports are included.

Calculation history

The server stores up to 50 entries in this session.

No calculations are stored yet.

Technical notes

Server validation protects every submitted value. CSRF tokens protect normal browser submissions. Output escaping reduces injection risks.

The calculator uses double-precision floating-point arithmetic. PHP BCMath detection can support future extensions. Current geometric square roots still require floating-point evaluation.

The same file exposes optional JSON output. Submit the form to this page with ?api=1. The response contains success, errors, and raw results.

Built-in formula tests are available through ?self_test=1. They verify standard, equilateral, invalid, and coordinate cases.

JavaScript improves diagrams and exports. Core calculations still work without JavaScript. The server remains the final validation authority.

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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.