news
What is the mathematical symbol for "nothing"?
The question might sound weird. But I have a situation coming up while writing a research paper. I will try to put it simply. I want to define a random va...
Apr 19, 2026
Archive: News
news
Calculate surface area of revolution with arc length formula
I'm working on arc length calculation and area of surface of revolution in calculus and I'm really quite stuck on the process of how to do this....
Apr 19, 2026
news
Is there a (what is the) intrinsic definition of boundary?
It is asked to show that the closed disk $\overline{D}^2=\{(x,y)\in \Bbb{R}^2:x^2+y^2\leq 1\}$ (with the topology induced from $\Bbb{R}^2$) is not a regul...
Apr 19, 2026
news
Stoke's Theorem to evaluate line integral of cylinder-plane intersection
I want to use Stokes' Theorem to evaluate the line integral $F\cdot dr$ $F = (-y^2, x, z^2)$ and $C$ is the curve of the intersection of the plane $y...
Apr 19, 2026
news
Unit vector of the direction of v?
I was going over some of my notes and I saw that I wrote the following under a Resolving the Vector heading in my Direction Angles notes: $$\vec u = \frac...
Apr 19, 2026
news
What is the negation of the statement "Every odd nmber is divisible by 2".
Intuitively,I think it is "no odd number is divisible by 2" or it could be "every odd number is not divisible by 2". Is this a trivial question or is ther...
Apr 19, 2026
news
Functions with subscripts?
In the equation: $f_\theta(x)=\theta_1x$ Is there a reason that $\theta$ might be a subscript of $f$ and not either a second parameter or left out of the ...
Apr 19, 2026
news
Can we find the GCD of a positive and negative number?
I'm trying to evaluate whether or not $\gcd(p,q) = \gcd(-p,q)$ for non-zero integers $p$ and $q$. I was wondering if it's possible to find $\gcd...
Apr 19, 2026
news
What is the Arctangent of Tangent?
This is probably just me misunderstanding trig properties. I remember from my trig days that $\tan(\arctan(x)) = x$ But I can't remember if that hold...
Apr 19, 2026
news
volume of a truncated cone that is not a frustum
I know the formula for a conical frustum is $$\frac{\pi h}{3}\left( r^2+rR+R^2 \right) $$ What would the formula be for the area of a truncated right circ...
Apr 19, 2026
