If someone didn’t learn enough trigonometry in school:
1+tan2c = cos2c/cos2c + sin2c/cos2c = (cos2c + sin2c)/cos2c = 1/cos2c;
sqrt(1/cos2c) = |sec c|
And here is for the people who still don't get the joke
The reading of the answer is very similar to the word “sexy”, which makes the whole sentence a reference to the song “Sexy and I Know It” by LMFAO.
I only remember useful things. And I consider these useful because I did some low level graphics programmed once and had to use them in practice. Once you understand why these things exist, it becomes that much easier.