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Mathematics 15 Online
OpenStudy (anonymous):

Find the real values of x for which the equation is valid.

OpenStudy (anonymous):

\[2\cos (x)=\sqrt{3}\cot (x)\]

OpenStudy (anonymous):

can you right cot (x) in terms of sin and cos

OpenStudy (anonymous):

***write nor right

OpenStudy (anonymous):

I wrote cot(x)=cos(x)/sin(x)

OpenStudy (anonymous):

And then i cancelled the cos(x)

OpenStudy (anonymous):

yup good

OpenStudy (anonymous):

And i was left with sin(x) = sqrt(3)/2

OpenStudy (anonymous):

now can you write what answer you got

OpenStudy (anonymous):

I then thought i can get infinite answers....

OpenStudy (anonymous):

So i wrote pi/3 and 2pi/3

OpenStudy (anonymous):

I think there are more solutions but i dont know how to writee them

OpenStudy (anonymous):

..... ok can you tell me what is th sin invers of \[\sin^{-1}( \frac{ \sqrt{3} }{ 2 })\]

OpenStudy (anonymous):

It is pi/3 and 2pi/3 between 0 and 2pi

OpenStudy (anonymous):

How you got 2pi/3

OpenStudy (anonymous):

I did pi - pi/3 because sin is also positive in that quadrant

OpenStudy (anonymous):

yes exactly.. so when we find inverse if get more values we take the lesser value usually.. for example 7pi/3 is also giving same answer but by using the concept above answer will b what?

OpenStudy (anonymous):

is it pi/3?

OpenStudy (anonymous):

yup it is

OpenStudy (anonymous):

But i need to state all the values for it

OpenStudy (anonymous):

so i need to write, pi/3, 2pi/3, 7pi/3, 8pi/3, 13pi/3, 14pi/3 .......

OpenStudy (anonymous):

How can i write this as a general solution

OpenStudy (anonymous):

ok.. first take a look at pi/3 and 7pi/3 what can you find

OpenStudy (anonymous):

any similarity?.. or relation... (clue can you relate with multiple of 2pi

OpenStudy (anonymous):

Oo i think i found it

OpenStudy (anonymous):

Is it pi/3 + 2kpi

OpenStudy (anonymous):

and 2pi/3 + 2kpi

OpenStudy (anonymous):

exactly.. ther you go... what is k...( no need to tll if you ar pretty sure)

OpenStudy (anonymous):

And one more thing

OpenStudy (anonymous):

Will i also need to evaluate cos(x)=0?

OpenStudy (anonymous):

??? not clear... cab you make it more clear?is it another question?

OpenStudy (anonymous):

** can

OpenStudy (anonymous):

if it is another qustion your answer is (2k+1)pi/2

OpenStudy (anonymous):

No same one

OpenStudy (anonymous):

wouldn't 2cos(x) = sqrt(3)cot(x) if cos(x) = 0 also

OpenStudy (anonymous):

am I clear?

OpenStudy (anonymous):

ok...... asuming a fuction itself is zero may not lad you to corrct ansewr... also... here the cos (x) cancels each other (ofcourse before assuming it zero) hence assuming cos (x) = 0 is wrong..

OpenStudy (anonymous):

**lead you to correct answer

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