Proof that $ \sin \sqrt{x}$ is not periodic function using contradiction method?
33628
Prove that $\sin(\sqrt x)$ not periodic
79419
Is $\sin \infty$ an indeterminate form?
97213
Why does $\sin(0)$ exist?
149447
Proving $\sin (x)=\cos (90^\circ-x)$
131140
Understanding ProofWiki's proof of differentiation of sine power series
11259
Prove $R\times S$ is not an integral domain
16253
Proof that $|\sin(nx)| \le n|\sin(x)|$
141273
When is $\sin(x)$ rational?
94244
$\sin \frac{1}{x}$ is not uniformly continuous on $[1, \infty]$
46642
Continuity of $\sin(x)/x$
2926
The contradiction method used to prove that the square root of a prime is irrational
3296
Proof That $\mathbb{R} \setminus \mathbb{Q}$ Is Not an $F_{\sigma}$ Set
13566
Is it possible to detect periodicity of an analytic function from its Taylor series coefficients at a point?
135774
Alternating roots of $f(x) = \exp(x) \sin(x) -1$ and $\exp(x)\cos(x) +1$
101329
Avoiding numerical cancellation question for $\sin x -\sin y$ for $x \approx y$
109189
Periodicity of a triginometric function
141522
$f$ is T periodic and $f(x) + f'(x) \ge 0 \Rightarrow f(x) \ge 0$