← All courses△Geometry
Shape and Angle
Proof-based plane geometry: angles, parallel lines, congruent and similar triangles, right-triangle trigonometry, polygons, circles, area, volume and transformations.
10 topics · 96 lessons about 44 hoursBefore this: Algebra 1 What you'll be able to do
- Write two-column and paragraph proofs
- Prove triangles congruent or similar and use the consequences
- Apply the circle theorems
- Compute areas and volumes of standard figures
Start the course
Go through each topic step by step — prose, worked examples, quick checks, and a timed practice round after every section.
Every test ends with a score by topic and a list of what to revisit. Test out of a topic with 80% or better to mark it mastered.
Topics
1.Core Ideas in Plain Terms
5 lessons Shapes and reasoning, in everyday language
2.Transformations
10 lessons Slides, flips, turns, and resizes on the coordinate plane
3.Points, Lines & Planes
8 lessons Foundations: undefined terms, segments, midpoints & distance
Naming, classifying, and solving for angle measures
5.Parallel & Perpendicular Lines
10 lessons Everything you need to name angles, find them, and work with slopes
6.Triangles & Congruence
10 lessons Classifying, angle rules, congruence shortcuts, and a first proof
Ratios, similar polygons & triangles, indirect measurement, midsegments & scaling
8.Right Triangles & Trig
11 lessons Pythagoras, special triangles, SOH-CAH-TOA, and angles of elevation
9.Quadrilaterals & Polygons
10 lessons Vocabulary, angle formulas, special quadrilaterals, and the family tree
Parts, circumference, area, angles, tangents, chords, and equations
11.Area & Volume
8 lessons Flat shapes, solid shapes, and the formulas that measure them
12.Course Review
10 lessons Every key definition, theorem, and formula from all ten units