A New Algebraic Proof of Heron's Formula?
21745
Proof of Heron's Formula for the area of a triangle
20346
'Algebraic' way to prove the boolean identity $a + \overline{a}*b = a + b$
101493
Prove that one diagonal of a quadrilateral bisects the other
106965
How to algebraically prove $\binom{n+m}{2} = nm + \binom{n}{2} + \binom{m}{2}$?
49806
Prove that $\frac{R/ \ker \phi}{(\ker \phi + J)/ \ker \phi} \cong \frac{S}{\phi(J)}$
102496
Derivation of the formula for the vertex of a parabola
140768
Proof of Vandermonde Matrix Inverse Formula
33104
Combinatorial Proof with Summation Identity
123967
Proof of a generating functions formula
117540
Proof of Dobinski's formula for Bell numbers
55869
Use the Maclaurin series to prove that $e^{i\theta} = cos(\theta) + isin(\theta)$
134
Prove that the expression is a perfect square
53244
Prove that $p \in \mathbb{R}[x]$ can be represented as a sum of squares of polynomials from $\mathbb{R}[x]$
53899
Proof of the Sherman-Morrison Formula
139588
Formulae for Catalan's constant.
35313
Proof of Euclid's Lemma
121469
Proof of observations on natural numbers being expressed as differences of squares.