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[Post New]21 Feb 2008 15:45:48 IST
    Subject: Re:Prove the following:
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sboosy (3063)

Blazing goIITian

Olaaa!! Perrrfect answer. 539  [723 rates]
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to prove :
ab = rr3 + r1r2
LHS= 2RsinA *2RsinB=4R2sinAsinB
RHS:
r=4Rsin(A/2)sin(B/2)sin(C/2)
r3=4Rcos(A/2)cos(B/2)sin(C/2)
r2=4Rcos(A/2)sin(B/2)cos(C/2)
r1=4Rsin(A/2)cos(B/2)cos(C/2)
so rr3= 4R2sin2(C/2) sinAsinB
r1r2=4R2cos2(C/2) sinAsinB
adding both
4R2sinAsinB [ sin2(C/2)+cos2(C/2)]
= 4R2sinAsinB
LHS = RHS
hence proved
 this reply: 5 points  (with 1 Olaaa!! Perrrfect answer.   in 1 votes )   [?]
 
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