Question
Sun September 15, 2013 By: Vishal
 

Tan1.Tan2............Tan89=

Expert Reply
Sun September 15, 2013

tan 1.tan 2.tan 3 ........... tan 87.tan 88.tan 89

= tan 1.tan 2.tan 3 ....... tan(90-3).tan(90-2).tan(90-1)

= tan1.tan2.tan3 ...... cot1.cot2.cot3 

= tan1.cot1.tan2.cot2[till tan 44 and cot 44]........ * tan45

= 1 * 1 [as tan 45o = 1 and tanA.cotA=1]

= 1

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