answer it

Asked by  | 26th Jun, 2011, 01:16: AM

Expert Answer:

sec ? - tan ? = 4 ------(1)

It is known that sec2?  - tan2?  = 1
So, (sec ? + tan ?) (sec ? - tan ?) = 1
(4) (sec ? + tan ?) = 1
=> (sec ? + tan ?) = 1/4 -----------(2)

Adding (1) + (2), we get,

2sec ? = 4 + (1/4) = 17/4
sec ? =17 / 8
So, cos ? = 8/ 17

Answered by  | 26th Jun, 2011, 12:57: PM

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