Alright, so one of my questions is CSC (angle) -5. When I plug CSC in my calculator, it says "math error." I'm using a Casio fx-300 MS, and using shi...

My regression textbook textbook says that $\sum_{i=1}^{n} (x_i - \overline{x}) = 0$. I know that: $\sum_{i=1}^{n} (x_i - \overline{x})(y_i - \overline{y})...

Conisder Lusin's Theorem (Folland Chap 2 Ex 44): If $f: [a,b] \rightarrow \mathbb{C}$ is Lebesgue measurable and $\epsilon > 0$, there is a compac...

What is the most unusual proof you know that $\sqrt{2}$ is irrational? Here is my favorite: Theorem: $\sqrt{2}$ is irrational. Proof: $3^2-2\cdot 2^2 = 1$...

I want to draw a graph of 8 vertices and 16 edges with maximum vertex connectivity and maximum edge connectivity and also draw a graph with minimum vertex...

That is, why is $\varphi(AB)=\varphi(A)\varphi(B)$, if $A$ and $B$ are two coprime positive integers? It's not just a technical trouble—I can't ...

I saw two less than signs on this Wikipedia article and I was wonder what they meant mathematically. http://en.wikipedia.org/wiki/German_tank_problem EDIT...

The question is: If $\tan(\theta) = -\frac{8}{15}$, and $\sin(\theta) > 0$, then find $\cos(\theta)$. What I did was draw a triangle on the unit circle...

If $n>1$ is integer and $1\le a \le n$ is integer such that $(a,n)\neq 1$ then prove there exist integer $1 \le b <n $ such that $ab \equiv 0(mod \;...

I know about collinear points (points lying on a same straight line). I know about collinear vector (parallel vectors). But, coming to collinear lines, I ...