△
Symbol  Format  Data 

△  Code Point 
U+25B3 
TeX 
\triangle 

SVG 
The triangle symbol (△) is used in math to reference a triangle in a diagram. Typically, the symbol is used in an expression like this:
In plain language, the expression can be read as the triangle formed by the three points , and . Read more …
The capital Greek letter Δ (Delta) is used in mathematics to represent the change in a variable.
The upside down triangle is an alternative to the nabla symbol to represent a gradient.