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Show that a cosA+bcosB+c"cos"C=(2Delta)/...

Show that a `cosA+bcosB+c"cos"C=(2Delta)/(R)`

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The correct Answer is:
`2(Delta)/(R)=R.H.S`
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SRISIRI PUBLICATION-PROPERTIES OF TRIANGLES-LAQ ,SAQ,VSAQ (2DHARDQ) (3DMIS.Q)
  1. In DeltaABC prove that (b-c)^(2)cos^(2).(A)/(2)+(b+c)^(2)sin^(2).(A)/(...

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  2. If tan.(C-A)/(2)=k cot.(B)/(2) then find k .

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  3. Show that (c-bcosA)/(b-c"cos"A)=(cosB)/(cosC)

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  4. In DeltaABC , " find " b cos ^(2).(C)/(2)+c cos^(2).(B)/(2)

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  5. If cot.(A)/(2)=(b+c)/(a) find angle B

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  6. Show that b^(2)sin2C+c^(2)sin2B=2bcsinA

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  7. In DeltaABC show that (b^(2)-c^(2))/(a^(2))=(sin(B-C))/(sin(B+C))

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  8. Show that a cosA+bcosB+c"cos"C=(2Delta)/(R)

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  9. Show that a^(2)sin2C+c^(2)sin2A=4Delta

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  10. In DeltaABC , prove that (1)/(r(1))+(1)/(r(2))+(1)/(r(3))=(1)/(r).

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  11. Show that rr(1)r(2)r(3)=Delta^(2)

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  12. If A=90^(@), " show that " 2(r+R)=b+c

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  13. If s = 12 and A=90^(@) then find the value of r(1)

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  14. If a = 18 , b=24 , c=30 , find r(1) .

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  15. If a , b, c are in A .P ., then show that 3tan.(A)/(2)tan.(C)/(2)=1

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  16. If acos^(2).(C)/(2)+c"cos"^(2)(A)/(2)=(3b)/(2), then show that a, b , ...

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  17. Two tress A and B are on the same side of a river . From a point C in ...

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  18. The upper 3//4^(th) portion of a vertical pole subtends an angle "Tan"...

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  19. AB is a vertical pole with B at the ground level and and A at the top ...

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  20. The angle of elevation of the toop point P of the vertical tower PQ of...

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