Proof for an equality in a triangle
130
What is a "harmonic quadruple"?
145783
How can I prove this inequality in a triangle: $\frac{1}{(b+c-a)} +\frac{1}{(c+a-b)} +\frac{1}{(a+b-c)} \gt \frac{1}{a} +\frac{1}{b} +\frac{1}{c}$?
14986
Proving a combinatorics equality: $\binom{r}{r} + \binom{r+1}{r} + \cdots + \binom{n}{r} = \binom{n+1}{r+1}$
131475
Example of the equality of an inequality
37744
Prove that given $a,b,c > 0$, it is possible to construct a triangle with sides of length $a,b,c$ if and only if $pa^2+qb^2 > pqc^2$
120148
prove this properties of triangles trigonometric question
83449
Proof with 3D vectors
83034
Triangle inequality square #2
39015
Prove the triangle inequality on the sphere $S^2$ in $\mathbb{R}^3$.
50417
Prove that the triangles $ABC$ and $AB^{'}C^{'}$ have the same incentre.
27954
Prove triangle inequality using the properties of absolute value
77253
Proof of Lagrange Identity
54170
Prove that $\triangle ABC$ is equilateral, If $(a+b-c)^{a}\cdot (b+c-a)^{b}\cdot (c+a-b)^{c}\geq a^a\cdot b^b\cdot c^c$
42446
Simple Elementary Algebra Equality
55975
Let $a$, $b$ and $c$ be the three sides of a triangle. Show that $\frac{a}{b+c-a}+\frac{b}{c+a-b} + \frac{c}{a+b-c}\geqslant3$.
94091
In $ \triangle ABC$ show that $ 1 \lt \cos A + \cos B + \cos C \le \frac 32$
29935
If $a, b, c, d>0$ and $abcd=1$ prove that an inequality holds true