Geometry
A complete geometry course, taught from the very beginning — no prior geometry assumed. One continuous track: every unit names what it builds on, every term is defined before it's used, and every idea comes with a figure you can touch.
Take the placement test
A quick adaptive test finds your level and marks the units most important for you.
The course — 13 units, in order
- 01Foundations: Points, Lines & AnglesPoints, lines, rays, segments and planes; measuring segments and angles; angle types, angle pairs, and bisectors.Start
- 02Reasoning & ProofFrom noticing patterns to proving facts: conjectures, if-then statements, and your first two-column proofs.Start
- 03Parallel & Perpendicular LinesTransversals and the angle pairs they create — which are congruent, which are supplementary — and proving lines parallel.Start
- 04Triangles & CongruenceTriangle types, the angle sum, the triangle inequality, and the congruence shortcuts SSS · SAS · ASA · AAS · HL.Start
- 05Relationships in TrianglesBisectors, medians, altitudes, the midsegment theorem, and inequalities inside a triangle.Start
- 06Quadrilaterals & PolygonsAngle sums for any polygon; parallelograms, rectangles, rhombi, squares, trapezoids, and kites — with proofs.Start
- 07SimilarityRatio and proportion, similar polygons, the AA · SSS · SAS similarity shortcuts, and the side-splitter theorem.Start
- 08Right Triangles & TrigonometryThe Pythagorean theorem, special right triangles, and sine · cosine · tangent with elevation and depression.Start
- 09CirclesRadius, chord, tangent, secant; central and inscribed angles; arcs; and the circle relationships.Start
- 10Area & PerimeterAreas of triangles, quadrilaterals and regular polygons; circumference, circle area, sectors, and composite figures.Start
- 11Surface Area & VolumePrisms, cylinders, pyramids, cones, and spheres — wrapping and filling 3-D solids.Start
- 12TransformationsTranslations, reflections, rotations, and dilations; symmetry; congruence and similarity re-seen through motion.Start
- 13Coordinate GeometryDistance, midpoint, and slope; equations of lines and circles; proofs with coordinates — the course capstone.Start