Lektionen
triangle 3 4 5
Introductory
Pythagorean theorem
a² + b² = c² in a right triangle, and where it comes from.
hypotenuse of 3 and 4
Introductory
Circles
Circumference, area and the meaning of π.
circle radius 2
Core
Polygons
Interior angles, apothem and area of regular polygons.
hexagon side 2
Core
Solids
Volume and surface area of spheres, cylinders, cones, boxes and pyramids.
volume of a sphere with radius 3
Core
Coordinate geometry
Distance, midpoint, slope and the equation of a line.
line through (0,1) and (2,5)
Introductory
Euclid's axioms and the structure of proof
Points, lines, the five postulates, and why geometry was the first axiomatic science.
triangle 5 5 5
Core
Congruent and similar triangles
SSS, SAS, ASA congruence, and similarity by scaling.
triangle 3 4 5
Core
Circle theorems
Inscribed angles, tangents, chords, and the angle in a semicircle.
circle radius 5
Core
Transformations: translation, rotation, reflection, dilation
Rigid motions and scalings, and the matrices that perform them.
inverse of [[0,-1],[1,0]]
Core
Solid geometry: prisms, pyramids, spheres
Volumes, surface areas and cross-sections in three dimensions.
volume of a cone with radius 3 height 4
Shapes, measured. Give three sides and get every angle, the area and a drawn figure; give a radius and get a sphere you can spin. Coordinate geometry connects it all to algebra.
Mehr Lektionen
Math Models and Geometry
Geometry
Euclid
Shapes
Coordinates and beyond
Einige dieser Lektionen sind aus offenen Texten angepasst: OpenStax Contemporary Mathematics, OpenStax Prealgebra 2e, Wikipedia. Jede Unterrichtsseite nennt ihre Quelle und Lizenz.
Hier verwendete Symbole
Tippen Sie auf jedes Symbol für die vollständige Definition, ein Bild und was jeder Buchstabe darin bedeutet.
Fragen, die die Leute stellen
Why does every triangle have angles adding to 180°?
Draw a line through one vertex parallel to the opposite side: the two alternate angles equal the other two angles of the triangle, and the three angles at the vertex lie on a straight line. That is Euclid's proof, and it is why the fact holds only on a flat plane.
When do I use the law of sines versus the law of cosines?
Cosines when you know three sides, or two sides and the angle between them. Sines when you know an angle and the side opposite it, plus one more piece.
What is the difference between area and perimeter?
Perimeter is the length of the boundary (one dimension, measured in metres); area is the amount of surface inside (two dimensions, square metres). Doubling every side doubles the perimeter but quadruples the area.
Geben Sie es ein oder zeichnen Sie es auf der Löserseite: jeder Schritt, ein Bild, die Antwort verborgen, bis Sie danach fragen. Lösen →
Weitere Teilgebiete
＋ Arithmetic𝑥 Algebra∿ Trigonometryƒ Precalculusσ Statistics & Probability⊢ Discrete Math & Logic∫ Calculus⊞ Linear Algebraℕ Number Theoryẏ Differential Equations∇ Multivariable Calculusε Real Analysis⋔ Combinatorics & Graph Theory∈ Set Theory & Logic𝔾 Abstract Algebra𝑃 Probability Theory≈ Numerical Methodsℂ Complex Analysis◎ Topologyμ Measure Theory‖·‖ Functional Analysisκ Differential Geometryπ₁ Algebraic Topology→ Category Theory∂ Partial Differential Equations≋ Fluid Dynamics∞ Frontiers