Δ
Symbol  Format  Data 

Δ  Code Point 
U+0394 
TeX 
\Delta 

SVG 
The capital Greek letter (capital delta) is used in math to represent change. Typically, the symbol is used in an expression like this:
In plain language, this means the change in the variable .
The Greek small letter delta (δ) is used in math as a variable. It appears in calculus in epsilondelta notation.
The slope of a line is calculated by finding the change in y over the change in x using two points on the line.