Q27 of 268 Page 4

Prove that :

tan 27° tan 45° tan 63°

Taking LHS

= tan 27° tan 45° tan 63°


=tan (90° - 27°) tan 45° tan 63° [∵ tan θ = cot (90° - θ)]


=cot 63° tan 45° tan 63°



= tan 45° [∵ tan 45° =1]


=1 =RHS


Hence Proved


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Prove that :

sin 42°. cos 48° + cos 42° . sin 48° = 1

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Prove that :

 28

Prove that :

tan 9°. tan 27°. tan 45°. tan 63°. tan 81° = 1

 29

Prove that :

sin 9°. sin 27°. sin 63°. sin 81°


= cos9°.cos27°.cos63°.cos81°