A point is that which has no part.
A line is breadthless length.
The ends of a line are points.
A straight line is a line which lies evenly with the points on itself.
A circle is a plane figure contained by one line, such that all straight lines from one point within the figure to the circumference are equal.
Let it be granted to draw a straight line from any point to any point.
To produce a finite straight line continuously in a straight line.
To describe a circle with any center and distance.
That all right angles are equal to one another.
That parallel behavior follows when interior angles on one side are less than two right angles.
Euclid's Elements is a classical collection of geometric definitions, postulates, propositions, and proofs. This game follows that structure by asking you to construct the figures behind the propositions, then submit your construction when it satisfies the goal.
Instruction Mode includes construction and proof notes. Master Mode gives the proposition with fewer hints.
Select moves editable points, lines, and circles. Point places a point. Line draws a straight segment from one point to another. Circle draws from a center point to a radius point. Erase removes editable lines and circles.
Use the color swatches before drawing to choose a construction color. Undo, Redo, Clear, and Submit manage the current proposition. Hold Shift and drag to pan the canvas; use the mouse wheel or a two-finger pinch to zoom.
This game can save completed levels in a browser cookie.