A Triangle is the 2-simplex. The study of triangles is called trigonometry. Its Bowers acronym is "trig".
Contents
Types of Triangle
By Sides
Equilateral
When all of the angles and edges of a triangle are equal a triangle is equilateral. Each angle must have a measure of exactly 60 degrees.
Isosceles
When a triangle has two equal sides, it is isosceles. It must also have two equal angles.
Scalene
A triangle with three unique side lengths is known as a scalene triangle.
By Angles
Acute
A triangle with all three angles smaller than 90 degrees is called an acute triangle. All equilateral triangles are also acute triangles.
Right-Angled
A triangle with one right angle is a right-angled triangle. Their side lengths follow the equation
, where c is the edge length of the side opposite the right angle.
Obtuse
A triangle where at least one angle is greater than 90 degrees is called an obtuse triangle.
Special Cases
A triangle with more than one right angle is usually degenerate, but can appear on the surface of a sphere. The same applies to a triangle with angles that sum to greater than 180 degrees, and to triangles that have any angle equal to 180 degrees.
See Also
Zeroth | First | Second | Third | Fourth | Fifth | Sixth | Seventh | Eighth | Ninth | Tenth | |
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Simplex | Point | Line | Triangle | Tetrahedron | Pentachoron | Hexateron | Heptapeton | Octaexon | Enneazetton | Decayotton | Hendecaxennon |
Hypercube | Point | Line | Square | Cube | Tesseract | Penteract | Hexeract | Hepteract | Octeract | Enneract | Dekeract |
Cross | Point | Line | Square | Octahedron | Hexadecachoron | Pentarss | Hexarss | Heptarss | Octarss | Ennearss | Decarss |
Hypersphere | Point | Line | Circle | Sphere | Glome | Hyperglome | Hexaphere | Heptaphere | Octaphere | Enneaphere | Decaphere |