Intereting Posts

$f\colon\mathbb R^n \rightarrow \mathbb R$ be a linear map with $f(0,0,0,\ldots,0)=0.$
Need help about $P\Gamma L_2(q)$, $q=4,3$
Adding a different constant to numerator and denominator
Prove that $$ is not a compact subset of $\mathbb{R}$ with the lower limit topology, i.e. open sets are of the form $[a,b)$.
Is $f(x)=1/x$ continuous on $(0,\infty)$?
GRE – Probability Question
Verification for the solution following differential equation!
Find all prime numbers satisfying…
I don't understand the 'idea' behind the method of characteristics
Is it true that arcwise isometry that is also a local homeomorphism is a local isometry?
eigen decomposition of an interesting matrix (general case)
Closure of image by polynomial of irreducible algebraic variety is also irreducible algebraic variety
Find vector field given curl
How to disprove this fallacy that derivatives of $x^2$ and $x+x+x+\cdots\ (x\text{ times})$ are not same.
Why every map $f : S^n \to T^n (n>1)$ has topological degree zero?

How to find the sine/cos/tangent/cotangent/cossec/sec of an angle:

In degrees

$\sin(23^{\circ}) =$ ?

- How to prove that the problem cannot be solved by the four Arithmetic Operations?
- Method to eliminate $x$ between the equation $x^2 + ax + b = 0$ and $xy+ l(x + y) + m = 0$
- Expressing $\sqrt{7+5\sqrt{2}}$ in the form $x+y\sqrt{2}$
- math fallacy problem: $-1= (-1)^3 = (-1)^{6/2} = \sqrt{(-1)^6}= 1$?
- Exponent of a number is a square root?
- Is $\sqrt{x^2}$ always $\pm x?$

In radians

$\sin(0.53) =$ ?

- How do you factor a quadratic expression, without using the formula?
- Finite Series $\sum_{k=1}^{n-1}\frac1{1-\cos(\frac{2k\pi}{n})}$
- What is $(-8)^\frac{2}{3}$?
- Prove : $\frac{\cos(x_1) +\cos(x_2) +\cdots+\cos(x_{10})}{\sin(x_1) +\sin(x_2) +\cdots+\sin(x_{10})} \ge 3$
- Non-probabilistic proofs of a binomial coefficient identity from a probability question
- How to convert the general form of ellipse equation to the standard form?
- Find intersection of two lines given subtended angle
- How to find $\lim_{x\to 0} \frac{1-\cos x \sqrt{\cos 2x}}{x^2}$
- AM-GM-HM Triplets
- How many resistors are needed?

In radians you can use the power series of the sine function to get very close to the true value. $$\sin (x) = x-\frac{x^3}{3!}+\frac{x^5}{5!}-\frac{x^7}{7!}+\frac{x^9}{9!}-\frac{x^{11}}{11!}+\cdots$$

The remaining functions have their own power series representations which can be used as well.

- Is it true that, in a Dedekind domain, all maximal ideals are prime?
- Proving that the tensor product is right exact
- Combinatorics/Task Dependency
- Formula for prime counting function
- Spaces with equal homotopy groups but different homology groups?
- How to prove this equality…
- Proving binomial coefficients identity: $\binom{r}{r} + \binom{r+1}{r} + \cdots + \binom{n}{r} = \binom{n+1}{r+1}$
- Isomorphism between dual space and bilinear forms
- How to prove that the Kronecker delta is the unique isotropic tensor of order 2?
- In the change-of-variables theorem, must $ϕ$ be globally injective?
- Is there a binary spigot algorithm for log(23) or log(89)?
- Proof of a matrix is positive semidefinite iff it can be written in the form $X'X$
- If $\arctan(x)+\arctan(y)+\arctan(z)=\pi/2$ how to show that $xy+yz+zx=1$?
- Functions defined by integrals (problem 10.23 from Apostol's Mathematical Analysis)
- A morphism of free modules that is an isomorphism upon dualization.