Given the particular ruler compass construction, prove that GKJHI is a regular pentagon
102297
Construction of a regular pentagon
23721
Prove that the Gaussian Integer's ring is a Euclidean domain
67949
$S_3$ permutes the elements of $\mathbb{R}^3$, show that $\sigma (x_1, x_2, x_3) = ( x_{\sigma^{-1}(1)}, x_{\sigma^{-1}(2)}, x_{\sigma^{-1}(3)})$.
88283
Proving the length of angle bisector
63277
Gordan’s lemma equivalent statement
16804
Prove whether or not a subgroup is normal in the dihedral group $D_4$
27088
How to draw a path to form a regular pentagon?
65873
A proof for Atiyah-Macdonald Exercise I.21.iii
118501
Proving the length of a circle's arc is proportional to the size of the angle
49984
Valid justification for algebraic manipulation of $\mathrm{d}y/\mathrm{d}x$?
101493
Prove that one diagonal of a quadrilateral bisects the other
66193
How to prove that a flat spacetime admits Minkowski coordinates?
22767
How to prove $3^\pi>\pi^3$ using algebra or geometry?
13993
Can we prove $ℝ^n ∖ \{\text{straight line}\}$ and $ℝ^n ∖ \text{\{an axis\}}$ homeomorphic by proving their complements homeomorphic?
13655
symbols of pencil, ruler and compass
133756
Geometric interpretation of $\det(A^T) = \det(A)$
73799
In a convex Quadrilateral ABCD, $\measuredangle ABC = \measuredangle BCD = 120^{\circ}$.Prove that: $ AC + BD \ge AB + BC + CD$