# Math Help - a ≡ b ?

1. ## a ≡ b ?

what does the symbol "≡" means? and how to read this equation a ≡ b?

2. It really depends on the context.

If you are working modulo some number n, then $a\equiv b$ means that a and b are congruent modulo n, which in turn means that n divides the difference a-b. For instance, $7\equiv 3\pmod{2}$, since 2 divides the difference 7-3.

If a and b are functions from the same domain, it could also mean that the two functions are identical, i.e. for all values of x in the domain, we have that a(x)=b(x). For example, the two functions $a(x)=\cos^2(x)+\sin^2(x)$ and $b(x)=1$ are identical on the set of real numbers.

It might not be one of these two options, though. Some context will help in answering the question.