Think of it this way: cos represents x, sin represents y, and tan is just sin divided by cos.
—SamanthaIMAGINARY AND COMPLEX NUMBERS
There might be a couple of questions on the Math Test that involve the letter i. If
you are not careful, you might assume that this is just another variable, as
innocent as x or y. But i is an imaginary number, equal to . The SAT is not
going to get too tricky with i; all you need to know is how i works when it is
raised to various powers: