Mathematics
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OpenStudy (anonymous):
Sollutions of triangles
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OpenStudy (anonymous):
In a triangle ABC
A:B:C = 3:5:4
Then
\[\huge a+b+c \sqrt{2}\]
is equal to
OpenStudy (anonymous):
(A) 2b
(B) 2c
(C) 3b
(D) 3a
OpenStudy (sidsiddhartha):
let
A=3k
B=5k\C=4k
OpenStudy (anonymous):
OK
OpenStudy (sidsiddhartha):
A+B+C=180
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OpenStudy (anonymous):
got it
OpenStudy (sidsiddhartha):
so
3k+4k+5k=180
k=15
OpenStudy (sidsiddhartha):
ok?
OpenStudy (anonymous):
then sine rule
OpenStudy (sidsiddhartha):
so we have now
A=45
B=75
C=60
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OpenStudy (sidsiddhartha):
yes
OpenStudy (anonymous):
Basically I was dong prove that type questions uptillnow so brain was not working
I got it now
OpenStudy (sidsiddhartha):
\[a+b+c \sqrt{2}=k(sinA+sinB+\sqrt{2} sinC)\]
OpenStudy (sidsiddhartha):
ok?
OpenStudy (anonymous):
yes
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OpenStudy (sidsiddhartha):
now just plug the values
OpenStudy (anonymous):
yeah
OpenStudy (sidsiddhartha):
\[a+b+\sqrt {2} c=k(\frac{ 1 }{ \sqrt{2} }+\frac{ \sqrt{3}+1 }{ 2\sqrt{2} }+\sqrt{2}\frac{ \sqrt{3} }{ 2 })\]
OpenStudy (anonymous):
I will do the rest
OpenStudy (sidsiddhartha):
ok :)
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OpenStudy (perl):
@sidsiddhartha how did you get that equation
a + b + c sqrt(2) = k ( sin A + sin B + sin C )
OpenStudy (sidsiddhartha):
using sine rule\[\frac{ sinA }{ a }=\frac{ sinB }{ b }=\frac{ sinC }{ c }\]
OpenStudy (perl):
i dont see how from that step you can get a + b + c = k ( sin A + sin B + sin C )
OpenStudy (anonymous):
al that equals a constant ktake the denominator to the right and see
OpenStudy (sidsiddhartha):
just used that property\[a=k.sinA\\b=k.sinB\\c=k.sinC\]
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OpenStudy (sidsiddhartha):
why @perl ?
OpenStudy (perl):
oh i thought you were using the same k from befor
OpenStudy (sidsiddhartha):
so whats your final answer udit?
OpenStudy (anonymous):
how to do after that
OpenStudy (anonymous):
I got answer in terms of newly defined "k" for sine rule but answer is in terms of b
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OpenStudy (anonymous):
b ,a ,c,
OpenStudy (sidsiddhartha):
from where i left--\[a+b+\sqrt{2}c=k(\frac{ 1 }{ \sqrt{2} }+\frac{ \sqrt{3}+1 }{ 2\sqrt{2} }+\frac{ \sqrt{3} }{ \sqrt{2} })\\=k \frac{ 2+\sqrt{3}+1+2\sqrt{3} }{ 2\sqrt{2} }=3k*\frac{ \sqrt{3}+1 }{ 2\sqrt{2} }=3k.\sin75^o=3b\]
thats what i'm getting
OpenStudy (sidsiddhartha):
ok gotta go now
OpenStudy (anonymous):
thanks ok bye!! =:)
OpenStudy (perl):
is 3b ok as a solution?
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OpenStudy (perl):
so there is no unique real number solution because you are only given the three angles , and you can dilate the triangle to any size
OpenStudy (sidsiddhartha):
answer check karke dekha