Geometry Course Vocabulary
In short: High school geometry vocabulary: 50 terms on proofs, congruence, similarity, circles, right-triangle trigonometry, and solids, each explained precisely in plain words with an example you can sketch.
A geometry course asks for exact language, and this high school geometry vocabulary page supplies it: postulate, theorem, bisector, perpendicular, congruent, similar, chord, tangent, arc, cross section. Every entry gives a precise definition, then a small example described so you can sketch it and test the idea yourself.
While writing a proof, you can check that you used the right term for a segment, angle, or circle part. Before an exam, print the pages and quiz yourself by drawing each term from memory, then compare with the entry. Matching words to pictures is the surest way to remember them under time pressure.
50 words on this page, each with a definition, a figure, a solved example and two quick questions.
Geometry Course Vocabulary: the full list
Geometry
- AA Similarity
- Angle
- Angle Bisector
- Arc (Circle)
- Arc Length
- Area of a Sector
- Cavalieri's Principle
- Central Angle
- Centroid
- Chord
- Circumcenter
- Conditional Statement
- Congruent Triangles
- Converse
- CPCTC
- Equation of a Circle
- Focus and Directrix
- HL Theorem (Hypotenuse-Leg)
- Incenter
- Inscribed Angle
- Isosceles Triangle Theorem
- Line Segment
- Midpoint Formula
- Midsegment of a Triangle
- Parallel Lines
- Parallelogram
- Perpendicular Bisector
- Perpendicular Lines
- Point, Line and Plane
- Ray
- Rhombus
- Rigid Transformation
- Same-Side Interior Angles
- Similar Triangles
- Solid of Revolution
- Tangent to a Circle
- Triangle Congruence (SSS, SAS, ASA, AAS)
- Two-Column Proof
- Volume of a Pyramid
Trigonometry
- Angle of Elevation and Depression
- Cosine
- Law of Cosines
- Law of Sines
- Radian
- Sine
- SOHCAHTOA
- Special Right Triangles
- Tangent (Trigonometric Ratio)