TRIGONOMETRY

Asked by  | 8th Oct, 2008, 04:29: PM

Expert Answer:

put secA= 1/cosA

LHS = (1-cos4A)cos8A  /  (1-cos8A) cos4A

= 2sin22A cos8A  / 2sin24A cos4A     ( 2sin24A cos4A = sin8A)

= 2sin22A cos8A  / sin4A sin8A          (sin4A = 2sin2A cos2A)

= 2sin22A cos8A  / 2sin2A cos2A sin8A

=sin2A cos8A  / cos2A sin8A

=tan2A / tan8A

Answered by  | 1st Dec, 2008, 10:10: PM

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