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Question: Answered & Verified by Expert
If A, B, C are the angle of ΔABC then cotAcotB+cotBcotC+cotAcotC=
MathematicsTrigonometric Ratios & IdentitiesMHT CETMHT CET 2018
Options:
  • A 0
  • B 1
  • C 2
  • D -1
Solution:
2343 Upvotes Verified Answer
The correct answer is: 1
Given A+B+C=π
⇒ A+B=π−C
⇒ cot( A+B )=cot( π−C )
⇒ cotAcotB−1 cotA+cotB =−cotC
⇒ cotAcotB−1=−cotAcotC−cotBcotC
⇒ cotAcotB+cotBcotC+cotAcotC=1

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