# Online Geometry Sketchpad - Dynamic Geometry Constructions and Measurements

> Free online geometry sketchpad: construct points, lines, circles and polygons, drag a free point and watch dependents update, with automatic measurements.

- URL: https://qilingtools.com/en/math/geometry-board
- Category: Math Tools (https://qilingtools.com/en/math)
- Tags: [Math](https://qilingtools.com/en/tags/math), [Education](https://qilingtools.com/en/tags/education)
- Last updated: 2026-10-26
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

A lightweight dynamic geometry board in the spirit of GeoGebra and The Geometer’s Sketchpad. Place a few free points, build segments, circles, perpendiculars, midpoints and intersections from them, then drag any free point — everything that depends on it moves along, and the lengths, angles and areas update live. Use it to explore theorems (do the medians of a triangle really meet in one point?), draw figures for lessons or check a construction for homework. Unlike the geometry calculator, which applies area and volume formulas, this is where you construct.

## How to use

1. Pick a tool from the toolbar: point, segment, circle, perpendicular, intersect, angle…
2. Click the points or lines it needs on the board (clicking empty space creates a point)
3. Switch back to Move and drag the blue free points to see the construction respond
4. Read coordinates, equations, lengths and areas in the object list, then export or copy a share link

## Features

- 14 tools: point, segment, line, ray, circle (centre + point), polygon, midpoint, perpendicular, parallel, intersect, angle, distance, delete and move
- Dependencies are tracked, so midpoints, intersections and perpendiculars recompute live while you drag
- Line–line, line–circle and circle–circle intersections, respecting the actual extent of segments and rays
- Automatic labels for segment lengths, angles (with a right-angle mark), distances and polygon areas
- Object list with point coordinates, slope-intercept equations, circle equations, areas and perimeters
- Grid with snapping, coordinate labels, wheel or pinch zoom and drag to pan
- Undo / redo (Ctrl+Z / Ctrl+Shift+Z); Delete removes the selected object and everything built on it
- Export SVG or a double-resolution PNG; autosaved locally, and share links contain the whole construction

## FAQ

### What is dynamic geometry?

A dynamic geometry board remembers how each object was built, not just where it is: midpoint D is stored as “the midpoint of A and B”. Drag A or B and D follows, along with every segment and angle that uses D — ideal for seeing which properties stay true as the figure changes.

### How do I find where two lines or circles meet?

Choose Intersect and click the two objects (lines, circles or one of each). Two lines give at most one point; anything involving a circle creates both intersection points at once. If the objects do not meet the point is shown as undefined, and it reappears as soon as you drag them into contact.

### How do I save and share a construction?

Your work is saved in this browser automatically, so a refresh does not lose it. “Copy share link” gives a URL that contains the entire construction (nothing is uploaded); anyone who opens it sees the same figure. You can also export SVG or PNG for slides and worksheets.

### How is this different from the geometry calculator?

The geometry calculator takes side lengths and radii and applies formulas for area, perimeter and volume. The sketchpad is for constructing figures on the coordinate plane and exploring them by dragging, with measurements taken from the construction itself. The two work well together.

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