vault backup: 2025-11-04 16:53:01

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2025-11-04 16:53:01 +01:00
parent 8e3b175d5d
commit 4bd845de6b
3 changed files with 78 additions and 7 deletions

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@@ -34,9 +34,37 @@
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@@ -36,3 +36,19 @@
- $f(x)=x^2,\;x\in[0,1]$ $D_f=[0,1]$
- ![[g2.png]]
- $$\begin{align}f(x)=3x+5\\g(x)=\frac{x-5}{3}\end{align}$$
- Exponential och logarithm
- Exponential: $f(x)=a^x$ för något $a>0$.
- Logaritm: $g(x)=\log_a(x)$ för något $a>0$
- $f$ och $g$ inverse till varandra: $y=a^x\Leftrightarrow\log_a(y)=x$.
- $D_f=\mathbb{R}=V_g,\;\;V_f=(0,\infty)=D_g$.
- Om $a>1,\;f,\;g$ är strängt växande.
- $\log_a{(xy)}=\log_a(x)+\log_a(y),\;\log_a(x/y)=\log_a(x)-\log_a(y)$
- $\log_a(x^b)=b\log_a(x)$
- Basbyte: $\log_a(x)=\frac{\log_b(x)}{\log_b(a)}\Leftrightarrow\log_b(x)=\log_b(a)\log_a(x)$. $a^x=b^{x\log_b(a)}$
- Ex: $$\begin{align}\text{Räkna }D_f\text{ för }f(x)=\log_{10}(x^2+2x-3)\\f\text{ är definierad för }x^2+2x-3>0\\\Leftrightarrow(x+3)(x-1)>0\\\Leftrightarrow x\in(-\infty,-3)\cup(1,\infty)\\D_f=(-\infty,-3)\cup(1,\infty)\\\\2^{x+3}>4\\\Leftrightarrow\log_2(2^{x+3})>\log_24\\\Leftrightarrow x+3>2\\\Leftrightarrow x>-1\\\\\log_{10}36\\=\log_{10}(2^2\times3^2)\\=\log_{10}(2^2)+\log_{10}(3^2)\\=2\log_{10}2+2\log_{10}3\\\\2^x=e^{x\log_e2}=e^{x\ln2}\\\log_2x=(\log_2e)\ln{x}\\=\frac{\ln x}{\ln 2}\end{align}$$
- **Def**: $\log{x}=\log_{10}x$
- **Def**: $\ln{x}=\log_ex$
- **Def**: $a^x=e^{x\log_ea}=e^{x\ln a},\;a\in(0,\infty)$
- **Def**: $\log_a1=0$
- **Def**: $\log_aa=1$
- **Def**: $\log_ab=\frac{1}{\log_ba}$

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Trigonometri.md Normal file
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@@ -0,0 +1,25 @@
- Radian:
- **Def**: *It is the SI unit for measuring angles (in the plane).*
- **Def**: *$1$ radian is defined as the angle subtended at the center by a circular arc of length equal to the radius*
- **Def**: *A general angle is measured in radians as the ration of the length an associated circular arc and the corresponding radius. That is $\theta=\frac{s}{r}\text{rad}$*
- **Def**: *Usually "$rad$" is omitted.*
- Ex: $$\begin{align}180^\circ=\pi\text{ rad}\\\frac{\pi}{3}\text{ rad}=30^\circ\\\frac{\pi}{4}\text{ rad}=45^\circ\\\frac{\pi}{3}\text{ rad}=60^\circ\\\frac{\pi}{2}\text{ rad}=90^\circ\\2\pi\text{ rad}=360^\circ\end{align}$$
- The right angled triangle
- **Def**: *The trigonometric functions: *$$\begin{align}\sin\theta=\frac{\text{perpendicular}}{\text{hypotenuse}}\\\cos\theta=\frac{\text{base}}{\text{hypotenuse}}\\\tan\theta=\frac{\text{perpendicular}}{\text{base}}\end{align}$$
- Dominains and ranges:
- $D_{\sin}=\mathbb{R}\;\;R_{\sin}=[-1,1]$
- $D_{\cos}=\mathbb{R}\;\;R_{\cos}=[-1,1]$
- $D_{\tan}=\mathbb{R}\setminus\{n\pi+\frac{\pi}{2}:n\in\mathbb{Z}\}\;\;R_{\tan}=(-\infty,\infty)$
- Useful relations
- $\sin(-\theta)=-\sin(\text{odd}),\cos(-\theta)=\cos\theta(\text{even})$
- Periodicity: $\sin(\theta+2n\pi)=\sin\theta,\cos(\theta+2n\pi)=\cos\theta,\tan(\theta+n\pi)=\tan\theta$
- Complementary angles: $\sin(\frac{\pi}{2}-\theta)=\cos\theta,\cos(\frac{\pi}{2}-\theta)=\sin\theta$
- Sift by $\pi$: $\sin(\theta\pm\pi)=-\sin\theta,\cos(\theta\pm\pi=-\cos\theta$
- Sum of angles: $\sin(\theta+\phi)=\sin\theta\times\cos\phi+\cos\theta\times\sin\phi,\cos(\theta+\phi)=\cos\theta\times\cos\phi-\sin\theta\times\sin\phi,\tan(\theta+\phi)=\frac{\tan\theta+\tan\phi}{1-\tan\theta\times\tan\phi}$
- Double angle: $\sin(2\theta)=2\sin\theta\cos\theta,\tan2\theta=\frac{2\tan\theta}{1-\tan^2\theta},\cos(2\theta)=\cos^2-\sin^2\theta=2\cos^2\theta-1=1-2\sin^2\theta$
- Half angle: $2\sin^2\frac{\theta}{2}=1-\cos\theta,2\cos^2\frac{\theta}{2}=1+\cos\theta$
- Solving trigonometric equations
- $\sin\theta=\sin{a}\Leftrightarrow\theta=\left\{\begin{align}a+2n\pi,n\in\mathbb{Z}\\\pi-a+2n\pi,n\in\mathbb{Z}\end{align}\right.$
- $\cos\theta=\cos{a}\Leftrightarrow\theta=\left\{\begin{align}a+2n\pi,n\in\mathbb{Z}\\-a+2n\pi,n\in{Z}\end{align}\right.$
- $\tan\theta=\tan{a}\Leftrightarrow\theta=a+n\pi,n\in\mathbb{Z}$
- Ex: Solve $\sin(x+\frac{\pi}{6})=\frac{\sqrt{3}}{2}$