1. ## Tan equivalence

how does

$tan(\frac{5}{4}) = tan(\frac{1}{4})$

Thanks.

2. They are not equal. What gave you the impression that they were?

3. I believe that you meant to ask 'how does $tan(\frac{5\pi}{4})=tan(\frac{\pi}{4})$

Look at the graph of tan(x):
Tan - Wolfram|Alpha
It repeats itself every $\pi$ radians. Do you understand why this is the case?