#Trigonometry
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$\tan \left(\frac{A}{2}+\frac{A}{2} \right)=\tan(A)$
Civil Service Pigeon
can u explain further
Expand the LHS and set it equal to 9/40
But it says to use the tan(A+B) formula to solve this
That's how you expand the LHS
๐
could u please do it on paper
i been trying for hours
and i couldnt
do you know how to do that by any chance
?
Send what you have
i scrapped all the papers
cuz im getting a panic attack
its currently 2 am and my exam is at 10
id apreciate it if u help me do this
b/c you should have the LHS is $$\frac{2\tan(A/2)}{1-\tan^2(A/2)}$$
Civil Service Pigeon
Mhm
@stone schooner do you know about trignometric ratios
the identities
?
yeah
i did this
is this correct
this is my formula logbook
provided by my school
tan(A)=9/40, not A=9/40
You should be able to rearrange this as a quadratic in tan(A/2) and solve
$\frac{2\tan(A/2)}{1-\tan^2 (A/2)}=\frac{9}{40}$
Civil Service Pigeon
This implies $80\tan(A/2)=9-9\tan^2(A/2)$
Civil Service Pigeon
From here, it's a quadratic in tan(A/2)
and i just solve for a/2
?
but bro
they tell me not to use this formula
u used this one
they want this one
Setting A=B yields the tan(2A) formula
I just skipped the step of combining like terms
tan(A/2)*
If you want to be extra explicit, you can show this step
so
a = 4/90
and
b = a/2
What...
jusi
b = -a/2
we gonna fail @rocky fossil
howd we find that?
using the formula
tan(a+b) = tanA/2
so a +b = a/2
b = a/2 - a
b = -a/2
oh
You do notice that the A in the given formula and the A in the tan(A)=9/40 aren't the same, right?
Here's how to use the formula for tangent of the sum of angles, tan(A+B), to find the value of tan(A/2), given tan(A) = 9/40.
From the formula for tangent of the sum of angles, we have:
tan(A+B) = (tan(A) + tan(B)) / (1 - tan(A)tan(B))
Let's set B = A/2, so that we can use this formula to find tan(A/2). Then:
tan(A+A/2) = (tan(A) + tan(A/2)) / (1 - tan(A)tan(A/2))
We know that tan(A) = 9/40, so we can substitute this in:
tan(3A/2) = (9/40 + tan(A/2)) / (1 - 9/40 * tan(A/2))
We can solve for tan(A/2) by rearranging and simplifying:
(9/40 + tan(A/2)) / (1 - 9/40 * tan(A/2)) = tan(3A/2)
Multiplying both sides by 1 - 9/40 * tan(A/2), we get:
9/40 + tan(A/2) = (1 - 9/40 * tan(A/2)) * tan(3A/2)
Expanding the right side and collecting terms, we get:
9/40 + tan(A/2) = tan(3A/2) - 9/40 * tan(A/2) * tan(3A/2)
Rearranging and factoring out tan(A/2), we get:
tan(A/2) * (9/40 * tan(3A/2) + 1) = tan(3A/2) - 9/40
Solving for tan(A/2), we get:
tan(A/2) = (tan(3A/2) - 9/40) / (9/40 * tan(3A/2) + 1)
We can substitute the value of tan(3A/2) using the formula for tangent of the sum of angles again:
tan(3A/2) = (tan(A) + tan(A/2)) / (1 - tan(A)tan(A/2))
Substituting the value of tan(A) and simplifying, we get:
tan(3A/2) = (9/40 + tan(A/2)) / (1 - 9/40 tan(A/2))
Substituting this into the expression we derived for tan(A/2), we get:
tan(A/2) = ([(9/40 + tan(A/2)) / (1 - 9/40 tan(A/2))] - 9/40) / (9/40 * [(9/40 + tan(A/2)) / (1 - 9/40 tan(A/2))] + 1)
Simplifying, we get:
tan(A/2) = (9/31) * tan(A/2)
Therefore, tan(A/2) = 9/31.
Hence, the value of tan(A/2) is 9/31.
tbh idk waht to do after combining them
what
i
love
u
didnt even read it yet
but man ily
,w find tan(A/2) if tan(A)=9/40
,w tan((1/2)(arctan(9/40))
wait a sec bro
so after combining
the terms
what do we do
remove the denominator?
Once you have $\frac{2\tan(A/2)}{1-\tan^2 (A/2)}=\frac{9}{40}$, yes, you can multiply both sides by the denominator to turn the equation into a quadratic
Civil Service Pigeon
@rocky fossil @solemn cobalt is him
after turning it into a quadratic what should i do
Take a common denominator
they dont want the value of a
they jus want u to find tanA/2 on one side
on its own
You can solve for tan(A/2) since it's a quadratic in tan(A/2)
And the question explicitly asks for tan(A/2), not A/2, so idk where you got that from
One of the cases is rejected because of the quadrant A lies in (based off the sign of the extraneous solution)
my bad
BETT
thx so much
G
Anything else?
Especially @stone schooner since you're the one who opened the channel
Cause if not I'm going to close this
if u have the time
ye
to go fully through the question
@solemn cobalt are ur dms open
to find tanA/2
so we can make sure
we did
the right shi
that would be great
if not
Sure, lemme know what you get
bet
Yeh
๐
$-9\tan^{2}\left(\frac{a}{2}\right)\ +80\tan\left(\frac{a}{2}\right)\ +9=0$
jimmy
supposedly
how to fucking do this ๐
and it cant solve it
You should be able to factor it
civil is a genius wait
Are you and jusi friends?
I assume you'll explain it then?
its our mock
yup
thx
Have great day!