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Mathematics 22 Online
OpenStudy (kkbrookly):

Help please! I will give a medal and fan!

OpenStudy (kkbrookly):

Write the equation for the following graph:

OpenStudy (anonymous):

i dont know

OpenStudy (mathmath333):

it is a little similar to graph of \(y=\tan x\)

OpenStudy (kkbrookly):

The closest equation that I've found is y=3cot(x+3pi)

OpenStudy (mathmath333):

@freckles

OpenStudy (mathmath333):

\(y=3\cot(x+3\pi )\) does looks good https://www.desmos.com/calculator/kzivodheqc

OpenStudy (mathmath333):

https://www.desmos.com/calculator/tolq44vlj4 \(y=\cot(x+3\pi)\) looks better

OpenStudy (freckles):

I see observe the following things: period=pi zero @ x=3pi/8 zero vertical shift

OpenStudy (freckles):

and also I see the point (pi/4,1)

OpenStudy (freckles):

\[y=A \cot(x +C) \\ 0=A \cot( \frac{3\pi}{8}+C) \\ 0=\cot(\frac{3\pi}{8}+C) \\ \frac{\pi}{2}=\frac{3\pi}{8}+C \\ \frac{\pi}{8}=C \\ 1=A \cot(\frac{\pi}{4}+\frac{\pi}{8}) \\ 1=A \cot(\frac{3 \pi}{8})\] I can't figure out why it is not giving me the right graph :( I will come back and try later when I have food in my belly

OpenStudy (kkbrookly):

That's what I was doing last night and I couldn't figure it out.

OpenStudy (freckles):

3pi/8 wasn't the zero I counted a bit wrong should be the martkers are separated by (pi/4-0)/3=pi/12 units so the zero should be at 4pi/12=pi/3

OpenStudy (freckles):

\[0=A \cot(\frac{\pi}{3}+C) \\ \frac{\pi}{2}=\frac{\pi}{3}+C \\ \frac{\pi}{2}-\frac{\pi}{3}=C \\ \frac{\pi}{6}=C \\ y=A \cot(x+\frac{\pi}{6}) \\ 1=A \cot(\frac{\pi}{4}+\frac{\pi}{6}) \\ 1=A \cot(\frac{5 \pi}{12}) \\ \frac{1}{ \cot(\frac{5\pi}{12})}=A \] let me check this graph

OpenStudy (freckles):

i give up my numbers aren't working

OpenStudy (freckles):

lol maybe there is a vertical shift

OpenStudy (freckles):

because the 0 doesn't happen halfway between x=0 and x=pi

OpenStudy (freckles):

\[f(x)=A \cot(x+C)+D \\ \text{ the zero would have happened at } x=\frac{\pi}{2} \text{ but \it got shifted down 1 unit there } \\ f(x)=A \cot(x+D)-1\]

OpenStudy (freckles):

that D there was a type-o meant to keep it C

OpenStudy (freckles):

\[-1=A \cot(\frac{\pi}{2}+C)-1 \\ 0=A \cot(\frac{\pi}{2}+C) \\ \frac{\pi}{2}=\frac{\pi}{2}+C \\ C=0 \\ f(x)=A \cot(x)-1 \\ \text{ now \to find } A \\ (\frac{\pi}{4},1) \rightarrow 1=A \cot(\frac{\pi}{4})-1 \\ 2=A \cot(\frac{\pi}{4}) \\ 2=A \cdot 1\] \[f(x)=2 \cot(x)-1\]

OpenStudy (freckles):

so looking at that graph I'm a lot more happier I just did not think of a vertical shift at first :(

OpenStudy (freckles):

you cool with that @kkbrookly ?

OpenStudy (kkbrookly):

That equation looks very similar to the graph. Thank you! I'll use that one instead!

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