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Mathematics 15 Online
OpenStudy (anonymous):

Sollutions of triangles

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

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

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

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 :)

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\[a=k.sinA\\b=k.sinB\\c=k.sinC\]

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

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?

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

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