I've tried the double angles theorem and

Kaspaueru2
2021-12-31
Answered

Basically, write $\mathrm{cos}4x$ as a polynomial in $\mathrm{sin}x$ .

I've tried the double angles theorem and$\mathrm{cos}2x={\mathrm{cos}}^{2}x-{\mathrm{sin}}^{2}x$ . I'm still having trouble right now though.

I've tried the double angles theorem and

You can still ask an expert for help

rodclassique4r

Answered 2022-01-01
Author has **37** answers

scomparve5j

Answered 2022-01-02
Author has **38** answers

If you prefer we can use complex numbers

Let$z=\mathrm{cos}x+i\mathrm{sin}x$ . Using de Moivres

Let

Vasquez

Answered 2022-01-08
Author has **460** answers

Double angle theorem once:

Double angle theorem twice:

Expand chicken soup and rice:

To get it entirely in terms of

asked 2021-08-20

Let P(x, y) be the terminal point on the unit circle determined by t. Then

asked 2022-05-01

Proving $\frac{\mathrm{cos}2x}{1+\mathrm{sin}2x}=\mathrm{sec}2x-\mathrm{tan}2x$

I tried

$\frac{1-{\mathrm{sin}}^{2}x}{1+2\mathrm{sin}x\mathrm{cos}x}-\frac{1-{\mathrm{cos}}^{2}x}{1+2\mathrm{sin}x\mathrm{cos}x}$

but I couldn't simplify. I start with LHS.

I tried

but I couldn't simplify. I start with LHS.

asked 2022-04-08

Find:

$L=\underset{x\to 0}{lim}\frac{\mathrm{sin}(1-\frac{\mathrm{sin}\left(x\right)}{x})}{{x}^{2}}$

asked 2022-04-03

Solving $2\mathrm{sin}(\theta +17)=\frac{\mathrm{cos}(\theta +8)}{\mathrm{cos}(\theta +17)}$

asked 2022-01-14

how is this solved? $\underset{x\to 0}{lim}\frac{1}{{x}^{2}}(\left({\mathrm{tan}(x+\frac{\pi}{4})}^{\frac{1}{x}}-{e}^{2}\right)$

asked 2022-02-25

I recently determined that for all integers a and b such that $a\ne b$ and $b\ne 0$ .

$\mathrm{arctan}\left(\frac{a}{b}\right)+\frac{\pi}{4}=\mathrm{arctan}\left(\frac{b+a}{b-a}\right)$

asked 2022-03-30

Series $\sum _{k=1}^{n}\frac{\mathrm{tan}\frac{x}{{2}^{k}}}{{2}^{k-1}\mathrm{cos}\frac{x}{{2}^{k-1}}}$