In a triangle $ABC$, $\cos A = 3/5$ and $\cos B = 24/25$. Find the value of $\cos C$. Question: Is this even possible since cosine is adjacent over hypote...

How to sort vertices of a polygon in counter clockwise order? I want to create a function (algorithm) which compares two vectors $\vec v$ and $\vec u$ whi...

If the line integral can be interpreted as the area under the curve $C$ on a scalar field, then the surface integral would be the volume under a surface o...

I conducted a survey where participants inputted a range for their weekly tablet usage. For example, someone was able to say they used their tablet "11 - ...

Not sure if this is the right place to ask this but I searched and didn't find this question already asked. I am having a lot of trouble conceptually...

Find $\theta$ with $\sec(3\theta/2)=-2$ on the interval $[0, 2\pi]$. I started off with $\cos(3 \theta/2)=-1/2$, thus $3\theta/2 = 2\pi/3$, but I don'...

If $R$ is a ring, J is an ideal in $R$, and $I$ is an ideal of $J$ (with $J$ considered as a ring), does it follow that $I$ is an ideal of $R$? That is, i...

Given $X \sim \text{NBin}(n,p)$, I've seen two different calculations for $\mathbb{E} (X)$: \begin{align*} &1. \mathbb{E} (X) = \frac{n}{p}, \qua...

I am having some troubles with a question that subtracts powers. Solve for unknown: $$3^{x+4} - 5(3^x) = 684$$ I have a hunch that I should apply factoriz...

Let $A = \begin{bmatrix} 1 & 0 & -4 \\ 0 & 3 & -2 \\ -2 & 6 & 3 \end{bmatrix} $ and $b=\begin{bmatrix} 4 \\ 1 \\ ...