How to prove $\vec{a} \perp \vec{b}$ when $|\vec{a}-\vec{b}|=|\vec{a}+\vec{b}|$?
105367
Proving $||\vec{a}+\vec{b}|| = ||\vec{a}-\vec{b}|| \iff \vec{a} \perp \vec{b}$
95379
Prove that $V = V_1 \oplus V_2$ in the following
63535
Prove that if $A – C = B – C$ and $A\cap C = B\cap C$ then $A = B$
38200
Show that $(\mathbf{a}·\mathbf{a})(\mathbf{b}·\mathbf{b})-(\mathbf{a}·\mathbf{b})^2=(\mathbf{a}\times\mathbf{b})·(\mathbf{a}\times\mathbf{b})$?
101803
A\(B∩C) = (A\B) ∪ (A\C) how to prove?
67709
Stuck with proof for $\forall A\forall B(\mathcal{P}(A)\cup\mathcal{P}(B)=\mathcal{P}(A\cup B)\rightarrow A\subseteq B \vee B\subseteq A)$
120292
How to formally prove: if $d\mid da+b$, then $d\mid b$?
76188
Show $(W_1 + W_2 )^\perp = W_1^\perp \cap W_2^\perp$ and $W_1^\perp + W_2^\perp ⊆ (W_1 \cap W_2 )^\perp$
31465
Prove that if $a \mid b$ then $\gcd(a,b) = |a|$
102917
Proving statement - $(A \setminus B) \cup (A \setminus C) = B\Leftrightarrow A=B , C\cap B=\varnothing$
44403
Prove that $|a+b|^p \leq 2^p \{ |a|^p +|b|^p \}$
21807
on proving bac-cab rule, $\vec{A} \times ( \vec{B} \times \vec{C})= \vec{B} (\vec{A} \cdot\vec{C})- \vec{C}(\vec{A}\cdot\vec{B})$
111003
Prove that if $A\triangle B = C\triangle B$, then $A = C$
80255
How to prove that $|a-b|<\epsilon$ implies $|b|-\epsilon<|a|<|b|+\epsilon$?
151038
How to prove (A v B), (A → C), (B → D) therefore (C v D)
24098
Prove that $a$ divides $b$ and $b$ divides $a$ if and only if $a = \pm b$
3433
Proof if $a \vec v = 0$ then $a = 0$ or $\vec v = 0$