Published by:
CGP EDU Academic Team
Published on: August 13, 2026
In a Δ ABC, if a, b and c are in A.P., prove that cos A.cot 
, cos B.cot 
, and cos C.cot 
are in A.P.
Text Solution
Verified by ExpertsThe correct answer is:
CHECK THE SOLUTION.
cos A cot 
= 
= cot 
– sin A
Similarly cos B cot 
= cot 
– sin B
and cos C cot 
= cot 
– sin C
a, b, c are in A.P.
∴ sin A, sin B, sin C are also in A.P.
a, b, c are in A.P.
∴ cot 
, cot 
, cot 
are also in A.P.
∴ cot 
– sin A, cot 
– sin B, cot 
– sin C are also in A.P.
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