Could you please provide complete solution to the following question?

Asked by  | 24th Jun, 2008, 08:47: PM

Expert Answer:

we'll use cos3A = 4cos3A - 3cosA

multiply and divide by cos9

so we get

(4cos3 9 - 3cos9)(4cos227°-3) / cos9

=cos27(4cos227°-3) / cos9

= (4cos3 27 - 3cos27) / cos9

=cos81 / cos9

= sin 9 / cos9

= tan9

Answered by  | 14th Dec, 2008, 01:18: AM

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