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Nov
13
comment High School Math: Lines and Angles
If the lines are parallel, then the sum of these angles is 180 degrees. Since these lines cross, the sum of these angles is [greater than or less than??] 180 degrees. So $5x > 180$... you should be able to determine that three times a positive number is greater than two times a positive number.
Nov
13
comment Inverse Trigonometry Problem
Where are you getting this information? The number I transcribed above was from google.
Nov
13
comment Inverse Trigonometry Problem
Yeah... not sure where you're going with this. Are we to then take the cosine of 53 degrees? Because that's $0.601815023...$
Nov
13
comment Inverse Trigonometry Problem
Draw a triangle in the standard position (first quadrant, start from the x-axis, etc). The sine (opp/hyp) is 4/5, so label the opposite $4$ and the hypotenuse $5$. The adjacent side is $3$, by the Pythagorean theorem. Then take the cosine of the angle.
Nov
13
comment Convergence of the series $\sum\limits_{n = 4}^\infty {\frac{{n + 1}}{{(n + 5)(n + 4)(n - 3)}}}$?
It does, and don't call me Shirley.
Nov
12
comment Proof by definition limit equals to infinity
You show that the right-handed limit is infinity, while the left-handed limit is something else (viz. negative infinity).
Nov
12
comment Proof by definition limit equals to infinity
Are you familiar with the concept of left- and right-handed limits?
Nov
12
comment What is the period of $f(x) = \sin^4(x)+ \cos^4(x)$?
Nice edit :) +1
Nov
12
comment What is the period of $f(x) = \sin^4(x)+ \cos^4(x)$?
It's "solid" for those of us who already know how to do it.
Nov
12
comment Probability to win or lose tournament
Didn't you just cube the probability of a win to get $\dfrac{1}{27}$? Then $$p^3 > .4$$ for some $p$.
Nov
11
comment How to find middle point given angle and 2 other points?
The line through B and P is just line M. So the line through AB is perpendicular to M. Is has slope = ?? and you know the coordinates of one point already. You should be able to solve for the equation. Have you drawn a picture?
Nov
11
comment Prove that the function $f(x) = 3x + 7$ is continuous at every point $x_0\in\Bbb R$
You might consider \cdot for your multiplication.
Nov
11
comment How to prove $n=4k+3$ cannot be the sum of two squares, x and y are integers
Start with $n = x^2 + y^2$, and look at $x,y$ modulo 4.
Nov
11
comment Prove using the pigeonhole principle that there must be a power of 17 that ends in 00001
Where are you stuck?
Nov
10
revised Point estimate and margin of error
added 56 characters in body
Nov
10
comment Calculus: Ways to prove a limit.
They don't always say that.
Nov
9
comment Result of product with n=0
Yes, the additive identity.
Nov
9
answered Result of product with n=0
Nov
5
comment If $x^2-3x+9=0$, can we say $(x+3)(x^2-3x+9)$ is also $0$ hence $x^3=-27$?
$x = -3$ is not a solution to the original equation.
Nov
5
comment I was trying to solve a complex number to a power using de Moivre's Identity but got stuck.
(Let's not forget that an arctan is an angle. We know how to find the cosine of an angle - in a right triangle, of course - from SOHCAHTOA)