Grade 11Trigonometry
In triangle ABC prove that if alb, c are in AP then Cot(A/2), Cot(B/2), Cot (C/2) are in AP
In triangle ABC prove that if alb, c are in AP then Cot(A/2), Cot(B/2), Cot (C/2) are in AP
1 Answer
Arun
Dear student
Let us assume that
CotA/2 , cot B/2, cotC/2 are in A.P.
s(s-a)/delta, s(s-b)/delta, s(s-c)/delta ....A.P.
Multiply by delta/s
(s-a), (s-b), (s-c) .......A.P.
Now
Subtract s
-a, -b, -c .....A.P
Multiply by -1
a, b, c A.P.
Hence proved
Regards
Arun (askIITians forum expert)
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