Is a trigonometric function applied to a rational multiple of $\pi$ always algebraic?
51647
Proof that a trigonometric function of a rational angle must be non-transcendental
120906
Is there a proof that $\pi \times e$ is irrational?
55302
Rational values of trigonometric functions
150576
When is an Integer a Rational Number, and are All Ratios Rational, Even $\frac{\sqrt{7}}{2}$?
44400
$e^{2\pi i x} = (e^{2\pi i})^x$: What happens if x is rational?
147363
Is $\large \frac {\pi}{e}$ rational, irrational, or trandescendal?
83913
Rational solutions of Pell's equation
149381
Relating the base-p periodic expansion of a rational to its p-adic representation
53191
Showing a meromorphic function is rational
148310
Showing rational numbers are algebraic
143054
Can you raise $\pi$ to a real power to make it rational?
49984
Valid justification for algebraic manipulation of $\mathrm{d}y/\mathrm{d}x$?
118374
Is there a proof that $\pi$ is an irrational number?
83363
Finding the real root of a cubic algebraically
104548
Geometric proof for irrationality of $\pi$
61794
Interesting and unexpected applications of $\pi$
40087
Using Modularity Theorem and Ribet's Theorem to disprove existence of rational solutions