In △ABC, BD : DC = CE : EA = AF : FB = 1:4. Let K, L and M are points of intersection of AD, BE and CF, as shown on the picture...
123465
In triangle $ABC$, $AA_1$, $BB_1$, $CC_1$ divide sides in ratio of $1: 2$ and meet at $M$, $K$, $L$. Find area relation of $KLM$ and $ABC$
62565
Prove: the intersection of Fibonacci sequence and Mersenne sequence is just $\{1,3\}$
157155
How is HCF (c, d) = HCF (d, r), where c = dq +r (by Euclid's division lemma)?
59644
Proof of Cartesian product intersection
104068
Prove that $\forall a,b\in\mathbb{C} \exists c,d \in \mathbb{C}: c+d = a \land cd = b$
93686
In a UFD, lcm = product for coprimes: $\,(a,b)=1,\ a,b\mid c\Rightarrow ab\mid c$
84871
Determining the dimension of span$\{AB-BA : A,B \in M_{n \times n}(\mathbb R) \}$
6098
Let $f:A\rightarrow B$ and $C\subset B,D\subset B$. Prove that $f^{-1}(C\backslash D)=f^{-1}(C)\backslash f^{-1}(D)$
118716
If $ABCD$ is a cyclic quadrilateral, then $AC\cdot(AB\cdot BC+CD\cdot DA)=BD\cdot (DA\cdot AB+BC\cdot CD)$
64861
Intersection of open affines can be covered by open sets distinguished in *both*affines
106370
How do we construct the coslice category $C / \bf{C}$ given $\textbf{C}/C$ and prove that the two are equal?
15626
Relations of a~b iff b = ak^2
138199
Proof explanation $A\setminus B = A \setminus B \cap A$
70311
Trying to prove (A ∩ B) − C = (A − C) ∩ (B − C)
13167
Prove $A = (A \setminus B) \cup (A \cap B)$
21807
on proving bac-cab rule, $\vec{A} \times ( \vec{B} \times \vec{C})= \vec{B} (\vec{A} \cdot\vec{C})- \vec{C}(\vec{A}\cdot\vec{B})$
105594
Fixed point, union of $\aleph_0, \aleph_{\aleph_0},\aleph_{\aleph_{\aleph_0}}\dots$ [see Noah's comment on notation]