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Mathematics 13 Online
OpenStudy (anonymous):

arccot(0)

OpenStudy (anonymous):

the number whose cotangent is zero since \[\cot(x)=\frac{\cos(x)}{\sin(x)}\] it is also the number whose cosine is zero

OpenStudy (anonymous):

pi/2

OpenStudy (anonymous):

that will do it

OpenStudy (anonymous):

so arccot(-1)

OpenStudy (anonymous):

the number whose cosine is -1?

OpenStudy (anonymous):

no, it is the number whose COTANGENT is \(-1\)

OpenStudy (anonymous):

the reason it worked for the first answer is because a fraction is only zero if the numerator is zero so since \[\cot(x)=\frac{\cos(x)}{\sin(x)}\] it is only zero if \(\cos(x)=0\)

OpenStudy (anonymous):

but for that one you need to know where \[\frac{\cos(x)}{\sin(x)}=-1\]

OpenStudy (anonymous):

it is where cosine and sine are the same number, but of opposite sign

OpenStudy (anonymous):

3pi/4

OpenStudy (anonymous):

7pi/4

OpenStudy (anonymous):

careful here

OpenStudy (anonymous):

it is \(-1\) and an infinite number of places, you have to find the one in the right range

OpenStudy (anonymous):

eek what is the range?

OpenStudy (anonymous):

ok you have a function that is periodic, so it is certainly not one to one in order to make the inverse a function, you have to restrict the range of the inverse so that everyone gets the same answer notice that you provided two answers, but as a function it can only have one output per input

OpenStudy (anonymous):

i believe traditionally the range of arccotangent is \([0,\pi]\)

OpenStudy (anonymous):

so your first answer of \(\frac{3\pi}{4}\) is the right answer, the second answer is not right, because it is not in the range or arccotangent

OpenStudy (anonymous):

okay yes.. I remember that.

OpenStudy (anonymous):

so that claculators can work :-)

OpenStudy (anonymous):

you should help me:)))

OpenStudy (anonymous):

lol also so you have a well defined function

OpenStudy (anonymous):

so, how would I approach arccot(sqrt3)

OpenStudy (anonymous):

it is where you have \[\frac{\frac{\sqrt{3}}{2}}{\frac{1}{2}}\] for \[\frac{\cos(x)}{\sin(x)}\]

OpenStudy (anonymous):

pi/6

OpenStudy (anonymous):

i.e. where \[\cos(x)=\frac{\sqrt{3}}{2}\] and \[\sin(x)=\frac{1}{2}\] a very familiar pair

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

you make it seem so easy!

OpenStudy (anonymous):

last one..

OpenStudy (anonymous):

arctan(tan(5pi/4))

OpenStudy (anonymous):

then I have about 50 more to do on my own :-\

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