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Dr. Geo Tutorials: Getting Started with Dynamic Geometry

Dr. Geo is a dynamic geometry environment that helps you build, explore, and experiment with geometric constructions interactively. This tutorial introduces the core concepts and step‑by‑step workflows to get you started creating triangles, circles, transformations, and simple proofs.

1. What you’ll need

• A computer or tablet with Dr. Geo installed or access to the web version.
• Basic familiarity with points, lines, and circles.
• A goal: a simple construction to practice (e.g., perpendicular bisector, triangle medians).

2. Interface overview

• Toolbar: tools for creating points, lines, segments, circles, polygons, and text.
• Canvas: where you place and manipulate objects.
• Inspector / Properties: shows object attributes (coordinates, length, color) and lets you lock or hide objects.
• Construction history / algebra pane: lists objects and their defining relationships.

3. First construction — Create a triangle and its medians

1. Select the Point tool and place three points A, B, C on the canvas.
2. Choose the Polygon or Segment tool to connect A→B→C→A to form triangle ABC.
3. To build a median from A: select the Midpoint tool and click segment BC to create M (the midpoint of BC).
4. Use the Segment tool to draw AM. Repeat midpoints for the other sides and draw the remaining medians.
5. Optionally, select all three medians and change their color in the Inspector to highlight them.

4. Adding measures and constraints

• Display lengths or angles: select a segment or angle and enable its measurement in the Inspector.
• Constrain objects: use the Perpendicular, Parallel, or Equal Length tools to enforce geometric conditions so constructions remain valid when moved.
• Use numeric input for precision: many tools accept typed coordinates or lengths.

5. Exploring transformations

1. Create an initial shape (triangle or polygon).
2. Select the Transformation menu and choose a transformation: translation, rotation (specify center and angle), reflection (choose a line), or dilation (center and scale).
3. Apply the transformation to see how the figure maps; toggle trace options to visualize paths.

6. Interactive exploration and dragging

• Drag base points to see dependent objects update dynamically — a powerful way to develop intuition.
• Use the Animation feature on a point (set it to move along a path or rotate) to observe continuous changes.

7. Constructing proofs and dependencies

• Use the construction history/algebra pane to follow how each object is defined.
• Show or hide auxiliary objects used in proofs (e.g., perpendiculars, circles) to keep diagrams clean.
• Label key intersection or concurrency points and verify relationships (e.g., medians intersect at centroid).

8. Saving, exporting, and sharing

• Save your work in Dr. Geo’s native format to preserve constructions and dependencies.
• Export diagrams as PNG or SVG for use in documents or presentations.
• Share files with students or colleagues so they can interact with the same construction.

9. Tips and best practices

• Start with the simplest construction, then add constraints gradually.
• Name objects clearly (A, B, M, centroid) to keep the algebra pane readable.
• Use color and line styles to differentiate given elements, construction steps, and results.
• Keep a copied working file before experimenting with complex transformations.

10. Next steps and practice exercises

• Construct perpendicular bisectors and the circumcenter.
• Build angle bisectors and find the incenter of a triangle.
• Create a locus problem: trace the path of a point satisfying a condition (e.g., fixed sum of distances).
• Recreate classical theorems (Euler line, nine-point circle) interactively.

Dr. Geo makes geometry hands‑on: start small, use constraints for robustness, and rely on dynamic dragging to turn static theorems into living experiments.