What does the Fraktur-R or Re stand for in math?

Question

I have an assignment where we are suposed to find the angle between two complex vectors and we have been given the formula to try to work out the problem and were told by the prof. that he got it from wikipedia. I went to the page to try to figure out what that fancy R meant and I found this instead and still no clue as to the R or Re meant, any help?

Answer 1

That's the "real part" of a complex number.
For example, $\Re(2+3i)=2$. (Also written as: $\operatorname{Re}(2+3i)=2$.)

There is also a symbol for the "imaginary part."
For example, $\Im(2+3i)=3$. (Also written as: $\operatorname{Im}(2+3i)=3$.)

In general, if $z=a+bi$, then $\Re(z)=a$ and $\Im(z)=b$.

Answer 2

This means the real part. For example, if $z = a+bi$, then Re$(z) = a$