Q. 295.0( 3 Votes )

Prove that :

sin 9°. sin 27°. sin 63°. sin 81°

= cos9°.cos27°.cos63°.cos81°

Answer :

Taking LHS

= sin 9° sin 27° sin 63° sin 81°


= cos (90° - 9°) cos (90° - 27°) cos (90° – 63°) cos (90°- 81°)


= cos 81° cos 63° cos 27° cos 9°


Or cos 9° cos 27° cos 63° cos 81° = RHS


Hence Proved


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