Unexpected result for trigonometric function
I'm trying to solve the following trig eqn using sage.
$$sin(x)-cos(x) = 0$$
Hand calculation give me the result of: $$x=\frac{\pi}{4} + n\pi$$
However, the solve() function gives me a different result, why is that?:
sage:
sage: solve(sin(x)-cos(x) == 0, x, to_poly_solve=True)
[x == 1/4*pi + pi*z25]
sage:
Also, what's z in the answer? I haven't defined any such variable.