- 长三角 chángsānjiǎo Yangtze River DeltaAbbreviation for the [[长江三角洲|長江三角洲|chang2 jiang1 san1 jiao3 zhou1]]; an economically developed region centered on Shanghai and including parts of Jiangsu and Zhejiang provinces.
- 三角形 sānjiǎoxíng trianglethree-sided shape in geometry; also describes things with a similar shape, such as a delta
- 三角洲 sānjiǎozhōu deltathe landform at the mouth of a river formed by the accumulation of sediment, typically triangular or fan-shaped
- 珠江三角洲 zhūjiāngsānjiǎozhōu Pearl River DeltaThe Pearl River Delta region in southern China, including Guangzhou, Shenzhen, and Hong Kong
- 长江三角洲 chángjiāngsānjiǎozhōu Yangtze River DeltaThe fertile delta region surrounding the mouth of the Yangtze River; often used to refer to the economic area encompassing Shanghai, southern Jiangsu, and northern Zhejiang.
- 金三角 jīnsānjiǎo Golden TriangleThe Golden Triangle region of Southeast Asia, covering the mountainous border areas of Thailand, Myanmar, and Laos, known as a major drug production center.
- 铁三角 tiěsānjiǎo iron trianglea strong, stable, and unbreakable partnership or trio consisting of three parties
- 三角债 sānjiǎozhài triangular debtA situation where three or more parties are caught in a cycle of debt, with each party owing money to one and being owed money by another.
- 三角函数 sānjiǎohánshù trigonometric function; circular functionIn mathematics, functions related to the angles and sides of a triangle, such as sine, cosine, and tangent
- 三角裤 sānjiǎokù briefsbriefs; panties; triangular-shaped underpants
- 三角肌 sānjiǎojī deltoid muscleThe thick triangular muscle covering the shoulder joint
- 直角三角形 zhíjiǎosānjiǎoxíng right triangleright-angled triangle
- 三角恋爱 sānjiǎoliàn'ài love triangleA situation where one person is involved in romantic relationships with two other people at the same time; also refers to a romantic rivalry involving three people.
- 三角板 sānjiǎobǎn set squareA drawing tool used in drafting, typically made of wood or plastic, shaped like a right-angled triangle; also called a [[三角尺|三角尺|san1 jiao3 chi3]].
- 正三角形 zhèngsānjiǎoxíng equilateral trianglea triangle where all three sides and all three interior angles are equal
- 三角带 sānjiǎodài V-beltA type of rubber drive belt with a trapezoidal cross-section used on pulleys with grooves
- 百慕大三角 bǎimùdàsānjiǎo Bermuda Trianglethe Bermuda Triangle
- 三角铁 sānjiǎotiě triangleA percussion instrument made of a steel rod bent into a triangle shape and struck with a metal beater.
- 三角学 sānjiǎoxué trigonometryThe branch of mathematics that studies the relationships between the sides and angles of triangles and the properties of trigonometric functions
- 三角法 sānjiǎofǎ trigonometryThe branch of mathematics dealing with the relations of the sides and angles of triangles and with the relevant functions of any angles.
- 湄公河三角洲 méigōnghésānjiǎozhōu Mekong River DeltaThe alluvial delta in southern Vietnam formed by the Mekong River, known for its significant rice production.
- 三角尺 sānjiǎochǐ set squarePair of plastic or wooden triangles used for technical drawing and drafting to create straight lines and specific angles
- 长江三角洲经济区 chángjiāngsānjiǎozhōujīngjìqū Yangtze River Delta Economic ZoneEconomic region in eastern China including Shanghai, Zhejiang, and Jiangsu; centered around the Yangtze River Delta
- 三角皮带 sānjiǎopídài V-belta rubber belt with a trapezoidal cross-section used for power transmission in machinery
- 三角枫 sānjiǎofēng trident mapleA species of deciduous maple tree with three-lobed leaves, yellowish flowers, and fine wood used for furniture; often grown for its autumn foliage.
- 抚远三角洲 fǔyuǎnsānjiǎozhōu Bolshoi Ussuriisk IslandBolshoi Ussuriisk Island in the [[黑龙江|黑龍江|hei1 long2 jiang1]] river, at the mouth of the [[乌苏里江|烏蘇里江|wu1 su1 li3 jiang1]] opposite Khabarovsk; same as [[黑瞎子岛|黑瞎子島|hei1 xia1 zi5 dao3]]
- 三角座 sānjiǎozuò TriangulumTriangulum (constellation)
- 等角三角形 děngjiǎosānjiǎoxíng equiangular triangleA triangle where all three internal angles are equal; same as an [[等边三角形|等邊三角形|deng3 bian1 san1 jiao3 xing2]].
- 三角关系 sānjiǎoguānxi triangular relationshipA relationship involving three parties, especially a love triangle.
- 三角凳 sānjiǎodèng three-legged stool
- 三角巾 sānjiǎojīn triangular bandagea triangular cloth or sling used for medical purposes, such as wrapping a wound or supporting a broken arm
- 三角恐龙 sānjiǎokǒnglóng triceratopstriceratops; any dinosaur of the genus [[三角龙|三角龍|san1 jiao3 long2]]
- 三角旗 sānjiǎoqí pennanttriangular flag; pennant; burgee
- 三角术 sānjiǎoshù trigonometrymathematical discipline dealing with the relations of the sides and angles of triangles and with the relevant functions of any angles
- 三角柱 sānjiǎozhù triangular prisma prism with a triangular base and three rectangular or parallelogram sides
- 三角柱体 sānjiǎozhùtǐ triangular prisma three-dimensional solid with two parallel triangular bases and three rectangular sides
- 三角测量 sānjiǎocèliáng triangulationtriangulation; a method of surveying that uses triangles to calculate distances and areas
- 三角测量法 sānjiǎocèliángfǎ triangulationa method of finding a distance or location by measuring the angles of a triangle in surveying
- 三角腹带 sānjiǎofùdài athletic supporterathletic supporter; jockstrap
- 三角裤衩 sānjiǎokùchǎ briefsbriefs; panties; underpants
- 三角贸易 sānjiǎomàoyì triangular tradeTrade between three ports or regions, especially the historical 18th-century trade between West Africa, the Americas, and Europe
- 三角锥 sānjiǎozhuī triangular pyramida three-dimensional shape with four triangular faces, any of which can serve as the base; also called a tetrahedron
- 三角龙 sānjiǎolóng triceratopsa large herbivorous dinosaur from the late Cretaceous period with three horns and a large bony frill
- 不等边三角形 bùděngbiānsānjiǎoxíng scalene trianglea triangle where all three sides have different lengths
- 不规则三角形 bùguīzésānjiǎoxíng scalene trianglea triangle in which all three sides have different lengths; scalene triangle
- 二等边三角形 èrděngbiānsānjiǎoxíng isosceles trianglea triangle with at least two sides of equal length
- 南三角座 nánsānjiǎozuò Triangulum AustraleTriangulum Australe, a small constellation in the southern sky
- 帕斯卡三角形 pàsīkǎsānjiǎoxíng Pascal's triangle(math) Pascal's triangle; a triangular array of numbers where each number is the sum of the two directly above it
- 平面三角形 píngmiànsānjiǎoxíng plane trianglea triangle that exists within a two-dimensional plane
