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Grade 11Trigonometry

If A+B+C = 2S
SinS + Sin(S-A) + Sin(S-B)-sin(S-c)=?

Profile image of Abhinav Acharya
12 Years agoGrade 11
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1 Answer

Profile image of Rinkoo Gupta
ApprovedApproved Tutor Answer12 Years ago
sinS+sin(S-A)+sin(S-B)-sin(S-C)
{sinS-sin(S-C)}+{sin(S-A)+sin(S-B)}
2cos(2S-C)/2sin(C/2)+2sin(C/2)cos(B-A)/2
=2sinC/2[cos(A+B)/2 +cos(B-A)/2]
=2sinC/2 .[2cos(B/2)cos(A/2)]
=4cos(A/2)cos(B/2)sin(C/2)
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