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(bsecB+csecC)/(tanB+t a n C)=(csecC+asec...

`(bsecB+csecC)/(tanB+t a n C)=(csecC+asecA)/(tanC+t a n A)=(asecA+bsecB)/(tanA+t a n B)dot`

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Let a, b, c be the sides of any triangle ABC. Then by applying the sine rule, we get
`a/sinA=b/sinB=c/sinC=k`
`a=k sin A,b=ksinB,c=k sinC`
L.H.S=`(bsecB+csecC)/(tanB+t a n C)`
=`(b/cos B+c/cos C)/(sinB/cos B+sinC/cos C)[since secA=1/cos A and tanC=sin C/cos C]`
=`[(b cos C+c cos B)/(cos B cos C)]/[(sin B cos C+sin C cos B)/(cos C cos B)]`
=`(b cos C+c cos B)/(sin B cos C+sin C cos B)`
Substituting values from sine law, we get
...
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RD SHARMA-SINE AND COSINE FORMULAE AND THEIR APPLICATIONS-Solved Examples And Exercises
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  3. (bsecB+csecC)/(tanB+t a n C)=(csecC+asecA)/(tanC+t a n A)=(asecA+bsecB...

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  4. a(cosC-cosB)=2(b-c)cos^2A/2

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  5. a^2(cos^2B-cos^2C)+b^2(cos^2C-cos^2A)+c^2(cos^2A-cos^2B)=0 .

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  6. cos(2A)/a^2-cos(2B)/b^2 = 1/a^2-1/b^2

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  7. In a Delta A B C ,\ if\ a=2,\ b=3\ a n d\ sin A=2/3 then find /B

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  8. In any triangle A B C , prove that: (sin(B-C))/(sin(B+C))=(b^2-c^2)/(a...

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  9. In any triangle A B C , prove that: \ asin(B-C)+b s in(C-A)+csin(A-B)=...

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  10. In any triangle A B C , prove that: \ a^3sin(B-C)+b^3sin(C-A)+c^3sin(A...

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  11. In any triangle A B C prove that: sin((B-C)/2)=((b-c)/a)cosA/2

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  12. In any triangle A B C , prove that: (b-c)/(b+c)=(tan((B-C)/2))/(tan((B...

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  13. In any triangle A B C , prove that: acos((B+C)/2)=(b+c)sinA/2

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  14. A tree stands vertically on a hill side which makes an angle of 15^0 w...

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  15. A person, standing on the bank of a river, observes that the angle sub...

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  16. The angle of elevation of to be top point P of the vertical tower PQ o...

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  17. The elevation of a tower at a station A due North of it is alpha and ...

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  18. If in a Delta A B C ,\ /A=45^0,\ /B=60^0,\ a n d\ /C=75^0 , find the ...

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  19. If in any Delta A B C ,\ /C=105^0,/B=45^0, a=2, then find bdot

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  20. In Delta A B C ,\ if\ a=18 ,\ b=24\ a n d\ c=30\ a n d\ /C=90^0 find ...

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