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#1

$Old$ November 5th, 2009, 05:31 PM

valvan $valvan is offline$

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$Default$ i need help proving the indentity

(1/1-sinx)-(1/1+sinx)=2sectan
i got stumped on this one

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#2

$Old$ November 5th, 2009, 05:42 PM

alexmahone $alexmahone is offline$

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Originally Posted by valvan $View Post$

(1/1-sinx)-(1/1+sinx)=2sectan
i got stumped on this one

$\frac{1}{1-sinx}-\frac{1}{1+sinx}$

= $\frac{2sinx}{1-sin^2x}$

= $\frac{2sinx}{cos^2x}$

= $2\frac{1}{cosx}\frac{sinx}{cosx}$

= $2secxtanx$

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#3

$Old$ November 5th, 2009, 05:52 PM

valvan $valvan is offline$

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can you explain further how you got to
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#4

$Old$ November 5th, 2009, 07:59 PM

mathaddict $mathaddict is offline$

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Originally Posted by valvan $View Post$

can you explain further how you got to
=

HI

$\frac{1}{1-sinx}-\frac{1}{1+sinx}$

Just combine the fractions .

$\frac{1+\sin x}{(1-\sin x)(1+\sin x)}-\frac{1-\sin x}{(1+\sin x)(1-\sin x)}$

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#5

$Old$ November 5th, 2009, 10:49 PM

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= Numerator/Denomenator

Numerator = (1 + sin x) - (1 - sin x) = 1 + sin x - 1 + sin x = ?

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