Angular-flot $ .plot is not a function

Question

I use angular-flot for the chart, but when I render the page, it gives an error

$. plot is not a function.

AS I have jquery in my project.

Do i need to add jquery.flot.js files and other files?

if so, why should we use angular-flot?

Is it possible to use the direct add jQuery flot js and with $ (function) {...})