Capital Delta Symbol
The capital greek letter (Delta) is used in mathematics to represent change. Typically, the symbol is used in an expression like this:
In plain language, this means the change in the variable . So if was one value and now it has taken on a new value, represents the difference between the two values.
The slope of a line is calculated by finding the change in y over the change in x using two points on the line.
The Greek letter delta (δ).