#help-10
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what do you get?
yeah I tried but I just didint get it
Can maybe some help me like step for step
<@&286206848099549185> can someone help me it due tomorrow and i don't want to get in any trouble
@gritty dragon Has your question been resolved?
So, one of the methods to solve this is to solve one of the equations for either x or y and then substitute the variables of the other equation with your result.
I'd suggest solving 3y - 2x = 12 since it's the easier equation
Do you want to solve for x or for y?
yeah but i don't know hoe
I'll help you, don't worry
Let's solve for x, it doesn't really matter too much
oke
So you want to solve 3y - 2x = 12 for x, do you know how to do that?
I think you have to trace out the x
Yep, so you'll want to move everything that isn't x to the other side of the equation (i.e. a variable, a number)
okay
So what you want to do is subtract 3y from both sides, does that make sense?
It's
-2x = -3y + 12
oh yeah
Don't worry about that, it's an easy mistake to make
So now, you want the -2 to be gone as well. This means you have to divide both sides by -2
yes i understand
And then, the equation is...?
Exactly!
oke
And now, you enter 1.5y - 6 for every x that appears in the other equation
Then, the equation becomes ${(1.5y - 6)}^2+4y^2-8y+2*(1.5y-6)$
And the good thing about this is that you only have y's and no x's
Asgard
No, then you just solve the resulting equation for y
For now, just try to get everything with a y or a y^2 on one side, you're going to bump into a problem you can't solve with eihgth grade maths
okay so I can't answer that main question of 5x+5y
The problem is that you have to solve a quadratic equation and that's not possible without guessing (at least at the moment, you'll learn a formula for it later)
you mean a^2+bx+c
Oh, do you know that already? :D
yeah
Fantastic, then you can solve it
Dw :>
so i am calculating the first question right now
Mhm
Do you know how to solve the equation?
i am trying but if you could help me that would be great
Alright :D
thx ๐
So first, let's try to make the (1.5y - 6)^2 easier
Just multiply (1.5y - 6)*(1.5y - 6)
Not quite
oh
When squaring this sort of expression, you have to sort of multiply everything with everything
alr and how do we do that
Like this
oh but I thought I was doing that
Asgard
You only did a*a
oh yeah I see
That means our result is
$(1.5y)^2 + 3y*(-6) + (-6)^2$
yeah okay
Not 21.5 lmao
Sorry, the bot seemed to skip the asterisk
Asgard
oh np
Do you think you can solve this yourself?
yeah I am going to try
Alright, tell me if you're stuck
You seem to have dropped a y^2 somewhere ๐ค
oh
The 36 is correct, but it's -18y, not -15.75y
Okay, well the correct result is 2.25 y^2 - 18y + 36
That was almost correct! You just seem to have forgotten a ^2
Alright, so now we're at 2.25y^2 - 18y + 36 + 4y^2 - 8y + 2*(1.5y - 6)
yes
We just have to simplify one more thing
the 4y^2-8y+2*(1,5y-6) right
Exactly
And we'll make our lives a whole lot easier if we solve 2*(1.5y - 6) first
yeah so that is 3y-12
yes
And we can add things like 2.25y^2 and 4y^2 together to simplify everything even further
yes so we get 6,25y^2-26y+24
Exactly!
And the equation that we get is
6,25y^2-26y+24 = 3, but we need the 3 to be a zero, so just subtract three on both sides
๐
nice
Now, just enter the values into the formula for quadratic equations
Where exactly?
My calculator says math error
Could you send what you entered?
-26+ -26-4**-26* *21
So you entered +-?
Awesome :D
What's the result?
-2190.625
Hmmmm
I think so...
Give me a second
and the other answer was -1803.125
The two blue points are the ones we're looking for
They're pretty close to 1 and 3
oh then I was def. wrong
alr I will wait
There are two solutions, because it's a quadratic equation, but we need one value for y so we can continue to work with it
so we have to go back to 3y-2x=12
I don't think we made a mistake there, the problem is somewhere else
oh but if we want to know the value of y we have to trace back the y
Oh wait
Let's try both y for what we're going to do and see if one matches and the other one doesn't
Then we can rule it out
smart idea
So we have these two values, we just have to plug them into 3y-2x=12 and then solve for x
(Two times because we have two values)
yesh I get it
Awesome!
so 3y-2x=1.09 and 3y-2x=3,06
Not really, you have to substitute the y in there with the value, not the 12
so how would you write that down
Actually, we can do it even simpler
oe I like simple things
Just use the equation we got before:
x = 1.5y - 6
So
x_1 = 1.5*1.09 - 6
x_2 = 1.5*3.06 - 6
wait
what is wrong
There isn't a condition we have to fulfill, they want you to calculate a value...
what do you mean
The question was 5x + 5y = ?
And since we have two y and we will have two x, there will be two values for "?"
There will be
?_1 = -16.375
?_2 = 22.35
Hmmmm
we only have x and y what could it be
Well, we have two y, that means we can calculate two x, which will result in two equations
2 coordination
(I) 5*x_1 + 5*y_1 = ?_1
(II) 5*x_2 + 5*y_2 = ?_2
oooof I have no idea how to solve this tbh
oh its okay
Maybe another person can help you, try pinging the Helper role after 15 minutes
It's getting kind of late where I live unfortunately
We're in the same timezone :D
where do you live then
Germany ๐
i am from the netherlands
found this on a site
I don't know if its right i an just going to turn this in
Nice :D
Well, good luck with your homework!
Not sure about that ๐คทโโ๏ธ
thx man you too
I am to tired to go make math again so i am fine with it
well asgard thx for your help
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(sin20)(tan10+cot10) without a calculator
I just do not know how this is supposed to wkr
work
I converted into radians but this did not help my understanding
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โ
easy
its easy I just forget how to do it
2
yeah I know the answer
what is sin(20) in terms of cos(10) and sin(10)
its just how to do it
do u know?
u know sin(2a) = 2sin(a)cos(a)
yes
i did something stupid I think
(2sin10cos10)(sin10/cos10+cos10/sin10)
is this a valid step?
@strong vale
no this is fine
i dont know what to do next
now carry out the multiplication
how u get 4
(2sin10cos10)(sin10/cos10+cos10/sin10) start from here
and walk me through what u did
Wht is $2\sin{10}\cos{10} \times \frac{\sin{10}}{\cos{10}}$
azeem321
no im not solving it for you
i dont want u to solve for me
if i wanted an answer i just use my calculator
this looks like sin10/2sin10 but its not
carry out the multiplication and tell me your result
what is $\frac{\cos{10}}{\cos{10}}$
azeem321
its just
we did this topic months ago
yes
and my teacher randomly gives this assignment in the middle of studying logs
trigonometry will follow you for years in your math classes so get good at it
when u get rusty watch youtube videos
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isnt this correct?
,rotate 180
you mean 0/x-3?
no the rational fraction of "degree" 3/1
Cause then I'd say the result looks good to me
im supposed to use polynomial division on those 2 expressions and then integrate that
,w integrate (x^3-3xยฒ+2x-6)/(x-3)
looks good to me yeah
but this is different
no
how is there a x^2+6
expand it
ohh yeah ok
idk why it chose to write it that way
why did you integrate ?
i thought we were supposed to lol
don't see it written anywhere
so do i just write x^2+2?
what are you going to do if not try it
just post it
yes
i've tried this multiple times and have gotten it wrong
i would show you my work but its all messy
only y?
take the 9 out of the integral, don't bother with it
can i do this with tabular notation?
what do you call tabular notation ?
u & dv
if you want. I always forget how that looks but if that's what you're familiar with
Apply the formula, stop doing IBPs when you think it's not the easiest step anymore
should be -9(y/2+1/4)e^-2y
if you write this into a sum properly, you should get that
does the 9 get distributed in those parenthesis?
depends on how you want to write the final result. I put in factored form, you can expand if you want
you'll notice it's the same
so do i put the 9 over the 2 & 4?
you do whatever you want. There are many ways of writing this
software like that should accept all equivalent answers as correct
oh ok so then i have to do the bounds now
that's the issue
i got this answer before
and it was incorrect
looks wrong to me
its the same answer you got though
you forgot to subtract the value at 0
what do you mean?
u = t^3?
just differentiate t^3
ok ill do that
it's not hard when you got a polynomial, you take it's derivative until there's no polynomial anymore
guarantees the process ends
,w integrate -8t^3 e^(-2t) dt
looks good to me
yes
mateo you are the literal goat
loll yeah i know but i ask some other people and they just tell me idk what im doing and to completely relearn ibp
You look decently at easy with it yeah
so when i get someone that doesnt call me stupid im like enlightened lolll
could get some more practice as these are very easy IBPs that you shouldn't struggle with, but for a help channel that's exceeding expectations for sure
nah i mean that even when i asked a teacher he said i have to relearn everything
If you can do the exercises and you understand the method, the only thing left to "learn" is experience
yeah you're right
That's often the difference on these problems between the help-seeker and the help-giver: we've seen these problems before, we know how to solve them, sometimes in our heads, and we can use methods that we're familiar with that you're not, it allows us to do these things more easily
experience makes one hell of a difference
for sure i agree
tbh i just like to make sure what the u & dv is for this because im not always sure
it's whatever you want. Your job is to find the ones that work well
i put u=lnx
That's experience with a type of problem, you end up having many solutions from different techniques
yes
indeed
first intuition as well
reduces to a nice IBP
you can do that one on your own I think
I don't like the "I think" here
Actually this one can also be done without u-sub
i got 1/3x^3lnx-1/3x^2
,w integrate 8ln(x)/xยฒ
yeah thats different from what i got then
and clearly not by just a constant
Fun fact: sometimes that constant difference is very hard to spot and 2 expressions are both correct even though they look significantly different
true
but im not sure what i did wrong
i could have done 1/x(1/3)x^3 instead
but x^3/x = x^2
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anyone out there?
Cal 1
pls find someone else sorry
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@serene hatch Has your question been resolved?
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An integer is divisible by 11 if, and only if, the alternating sum of its digits is divisible by 11.
Does this prove both sides? or just the If n is divisible by 11 part?
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any idea how to solve this
QPS + QRS = 180
okay
so: b + d + c = 180
b + (180 - a) + c = 90
not really
do you rmb the angle inside a four sided is always 360?
since there is already 2 angles with 90, so a+d would be 360-90-90
yeah
angles of a quad = 360
wait
oh
so a + d = 180
im so confused
i hate geometry xd
back to here
since b + (180 - a) + c = 180
so: b+c = a
the 180 can be cancelled out each other
b + d + c = 180
a + d = 180
d = 180 - a
b + (180 - a) + c = 180
b + c = 180-180+a
b+c = a
done
i still dont get it wtf
get the first line
why does a + d = 180
angles on a line or?
it cant be coint <'s because we arent using paralell lines
rmb that all the 4 angles in a 4 sided polygon is always 360
since there is already got 2 angles which are 90, so a+d+90+90 = 360
you have to substitute and simplify to get b +c = a
PQR and PSR are both 90
why
rmb that: PQR + QRS + RSP + SPQ = 360
this was stated in the question and diagram
oh
OH
so
left side
and bottomleft side
and right side, bottom right side are 90
you
are in
a taken channel
oh sorry
yes
uhhh
idk where would i learn this
just written and explained simply in text form
i just cant understand it and ive got an even harder next question
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Heyo
Just wanted to clarify minor details for finding the determinant of a matrix
To find the determinant of a matrix, we just use laplace expansion on the top row of the matrix right?
And then that's all?
or any row or column, really
Wait wat rlly
So I can apply it to any single row or column
And it would find the determinant of the matrix
yes, so it's always a good idea to pick a row or column with a lot of zeroes
no prob ๐
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Are these triangles similar? I rotated it two different ways
One was similar, one was not
Just not sure which line segment UG corresponds to
If we make it correspond to FE, then SAS says the triangles are similar
But is it possible UG corresponds to BE, resulting in not similar?
I believe it is similar
angle UGA = angle BEF
UG/EF = GA/BE
The ratios of two lines and a corresponding angle is similar
And I think that's one of the proofs for similar triangles? I really don't trust myself
Yes that would be correct if we did it that way
Just wondering how we know for sure UG corresponds to EF
Because if we did UG/BE = other ratio, it will not work
Yeah since UG/BE doesn't work and UG/EF works, then UG corresponds to EF
Cus if u said triangle ABE is similar to triangle PLO for example, AB/PL = BE/LO
And AB/LO wouldn't be equals to PL/BE
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need help solving 1 and 3 please, asap
i looked up the first one but didnt understand anything too
,rotate
Oh lol very similar question to mine
If itโs above x axis, discriminant is <0
So arrange the equation to b^2-4ac <0
a and c are both gonna be 1 yes?
yes
Whatโs the answer?
its k>9
Ok one sec
Ok so when u multiply negative on both side of inequality
The inequality change sides
Is the answer k=11 ?
yes
Ok since the line intersects with curve
At one point bc tangent
U can equate the two equation
The line and curve equation, combine it into one
mhm
after than u should get a quad equation
Then u can use discriminant on it
Since itโs a tangent and touches at one point only
B^2-4ac=0
U should get k=11 after that
Np
in the 1st part of the 3rd question i do the same?
equal the both equations and solve them?
no. 3
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@rapid sentinel Has your question been resolved?
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so i got -30 in this question but it was incorect 5(a โb) if a = โ4 and b = โ2
be careful with negatives
?
you're subtracting negative two
so -6
no
this is why you have to be careful
think about it: if you take 2 and add negative 2, what do you get
?
what's 2 + -2
0
$a-b = a+(-b)$
so if 2 + -2 is 2 - 2 which is 0
what should 0 - -2, subtracting negative two from zero, be?
2
yep
subtracting -2 is the opposite of adding -2, and adding -2 is subtracting 2, so subtracting -2 is the same thing as adding 2
-(-a) = -1 * -1 * a = 1 * a = a
so now if we go back to -4 - -2
subtracting -2 is the same as adding 2, so this is -4 + 2
-2
yep
soo -10
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was it a mistake adding all 4 equations?
what's the question?
consider a polynomial Q
which has something to do with P
is my hint...
Q = P + ???
Let Q(x) = P(x) + R(x)
where R(x) is a polynomial to find
there is a sensible choice
hmm yeah
Q(x) = P(x) - P(5)
how will this help (it wont)
You try it out and see if u get anywhere.
The polynomial R to choose is not complicated, I can assure you
wait isn't $P(5)=(5)^4+a(5)^3+b(5)^2+c(5)+d$?
hyperlix26
Read what I said
I know what P(x) is
idk what the suitable R(x) is, wanted to make it equal to $(5)^4+a(5)^3+b(5)^2+c(5)+d$ but you said it wasn't equal to P(5) so that's not it
hyperlix26
what
oh nvm misread
I told you though
to find a suitable polynomial R(x)
And I also said it isnt complicated, it is simple
Write down a few guesses, see if they could help you any way.
If youre stuck, then say what R have you tried
hyperlix26
other than that I'm just making stuff up
if R(x) is a polynomial to find, why not make R(x)=Q(x)-P(x)?
that isnt even a choice
of R
Do you understand what a polynomial is?
yeah
I hinted a polynomial, so please realise it probably isnt a constant
So what example of R could you try
just name one
any
the same as P(x) but it doesn't make sense
ax+b?
if i randomly asked you for an example of a polynomial you wouldnt give me that
why the letters???
it still counts right?
An explicit example please?
2x+7?
Yes. Good.
Now I asked you to consider the new polynomial Q(1) = P(x) + 2x+7
What can we say using the given information?
It must still be of degree 4
But in particular what is Q(1) and so on
yeah
Now my hint was to pick a nice R(x)
what 'nice' means, try to figure it out
I will say now that Q(1) = 10 isn't helpful, so we need a better R
yeah I'm figuring out how to find a better R
Q(1) = ?
Q(2) = ?
Q(3) = ?
Q(4) = ?
First maybe think what we want these to be
for some useful information
Then you can find a good R
ok if I said we want those to be 0, how would it help?
If you know Q(1) = 0
What does this tell you about Q?
Is there a theorem you can use perhaps?
no idea
(x - 1)
no idea
maybe
I don't know what they are called here
For a polynomial f
f(a) = 0 <=> (x-a) is a factor of f(x)
For a polynomial f
f(a) = k <=> f(x) = (x-a)g(x) + k for some g
Factor and remainder theorems
yeah I've seen them but I don't understand them enough
if you can divide a polynomial by (x-a) and the result is 0, then (x-a) is a factor right?
no...
if i divide a polynomial by another polynomial I won't get 0
unless the original polynomial is 0
???
I mean the remainder
yh ok but thats just restating what i said
Try applying the theorem to this problem...
yeah basically that's all I know, I don't understand much from the remainder theorem
@balmy mortar anyways using this method, was it a mistake adding all 4 equations?
did you see me suggesting such a method?
no
Why would you end up doing such a thing in the direction I've been hinting at
also there arent even 4 polynomials
in your working
theres just 1
you mean 4 equations i suppose...
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how do we solve
$a_n = 3 a_{n - 1} + 10?$
Chromium
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rifififififfg you hibihgigog ficicciciocovo
Ok then.
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a(n)+5=3(a(n-1)+5)
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Hey everyone,
I need to calculate the radius and height of a cylinder, where the materiale usage is $20m^2$
The material usage can be calculated using this formula:
$O(r)=10\cdot r^{-1}+\pi+r^{2}$
I would assume that I could put 20 instead of $O(r)$, then isolate the radius $r$ but that gives me 3 solutions:
$20=10\cdot r^{-1}+\pi+r^{2} = $
r=2.221046 or r=โ2.743439 or r=0.522393
Juia
@late pond Has your question been resolved?
hello
by material usage does it mean the material used to cover the whole cylinder
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Yes, it does ๐
if that's the case then u could try using the formula for total surface area of cylinder
and equate it to 20
then you'd get values for the height as well
Juia
@potent dagger
no no
not the volume, i meant the surface area
volume has units of m^3
not m^2
Yeah ๐
the formula should be 2pir(r+h)
Yeah, but that gives me 2 unknowns (radius and height)
you do have two radius values tho
from what you solved earlier
tryin using each value and see what value of height u get
by using the equation we just discussed rn
Okay.
I have these two radius: r=2.221046 or r=0.522393
$20 = 2\cdot \pi \cdot 2.221046\cdot (2.221046+ h)$
Juia
Was the equation in the question given by the question or is it something you deduced
Juia
well you could create 2 simultaneous equations
one using O(r) = 20 and the other using surface area = 20
unless O(r) comes from the surface area equation in which case that probably won't work
essentially what im trying to say (or hope will work) is if you try to solve $$20 = 10r^{-1} + \pi r^2$$ $$20 = 2\pi r(r+h)$$
I can't believe you've done this
simultaneously
not sure if it will work but worth trying
like perhaps try finding an equation for $r$ using the first equation and then sub replace both $r$ in the second equation with the one you got from the first one
I can't believe you've done this
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Hello everyone! I am just struggling on how to find critical points with e problems ๐ฅฒ not sure if I am doing it right. Is it truly possible to not have critical points? If so what to do?
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<@&286206848099549185>
@rocky dove Has your question been resolved?
Use x=rcos(t), y=2rsin(t)
That becomes e^{-r^2sin(2t)}
Maximum when r=1 and sin(2t)=-1,minimal when r is 1 and sin(2t)=1
okay and I assume that helps me find the critical points
ooof okay i see what you are getting at
my question is how did u know that y=2rsin(t)? it just is? or its coming from a formula
just curious
its been a while ;-;
Np
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The question: Solve tanยฒฮธ = 2 * 1/cosฮธ for 0ยฐ โค ฮธ โค 360ยฐ.
The answer in the book was: 64.3ยฐ, 295.7ยฐ, 219.9ยฐ and 140.1ยฐ.
Here's my working out. Idk what I did wrong
<@&286206848099549185>
oh well .close
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I am stuck on part E. I am doing past paper questions and I am confused on how I am supposed to do this
what have you tried
Honestly, looking at the question hade made me not try but from the rules I know of, I can't think of a way to do it
i assume you know exponent laws? if not, google them
hint: rewrite 1/(9^x) with a base of 3
I got 1/3^2+x
how
Well, I learned exponent laws recently so there might be a flaw in my method but what I basically did was I assumed that since I can write 9 as 3^2, and when you multiply indices together you add the power so that's what I did
the 1/9 means 9^-1
refer back to your exponent laws
actually i think you just interpreted it incorrectly
you rewrote $9$
as $3^2$, yeah, but that gets you $(3^2)^x$
a disappointing son
the law you tried to apply states $a^b\cdot a^c=a^{b+c}$
a disappointing son
but you're raising an exponent to an exponent here, not multiplying
we've already established that. this isn't your problem
sorry again
that was inapropriate of me
@cosmic moon do you know how to convert 1/9x to an exponent
I did some working out, and got $3^2x-a+2^x$ = $3^2y-x$
AquaDrix
This basically
now you can cancel the 3s
that ain't right
so it becomes 2x - 1 + 2x = 2y
don't do people's work for them
also that's wrong
i didnt
yes, you did
that's not up for debate, i am looking at the work you did for him
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(Use a Double- or Half-Angle Formula to solve the equation in the interval [0, 2๐). (Enter your answers as a comma-separated list.)
tan(๐) + cot(๐) = 4 sin(2๐)
Let's start by getting all the trig functions in terms of theta
How do you get sin(2theta) in terms of just theta
u change it to sin(theta)cos(theta)
azeem321
i meant 2sin(theta)cos(theta)
azeem321
yep
now what
now u change tan and cot to sin(theta)/cos(theta) and cot to cos(theta)/sin(theta)
good and after doing that how about multiplying both sides by $\sin{\theta}\cos{\theta}$
azeem321
distribute the 8?
azeem321
what is s^2+c^2
1
Can you solve it now?
azeem321
u can do this now?
which I get pi/8 and -pi/8
notice the domain
and remember sin(2x) is periodic
with period pi
which means u can add/subtract pi
and it will be a solution
so if x=a is a solution
x=a+pi is a solution
x=a+pi+pi is a solution
x=a-pi is a soluition
but the question only wants the solutions between 0,2pi
we just add pi to both of them until we get all the possible solutions in the domain?
let's put this on a back burner
let me show u something important
this is the graph of sin(x)
Suppose we want to find all values of x, for which sin(x) = a
we know there is a solution at the red line
How do you get the second solution?
the next point where they intersect
yh
but most calculators won't give you that solution
so what algebra can u do to get that solution
look at the symmetry of the curve
$\sin{x} = \sin({\pi-x})$
azeem321
That would be for just sin(x)
to get the other answer
azeem321
because the period was half of what it was before?
3pi/8
So for $\sin{2x} = \frac{1}{\sqrt{2}} \implies x = \frac{\pi}{8}, \frac{3\pi}{8}$