Verify identity - need to help a student work through this

Trigonometry equalities, inequalities and expressions - sin, cos, tan, cot

Verify identity - need to help a student work through this

Postby Guest » Tue Nov 05, 2013 10:41 pm

(1-sec u)/(tan u) - (tan u)/(1 - sec u) = 2 cot u
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Re: Verify identity - need to help a student work through th

Postby Guest » Thu Nov 07, 2013 12:19 pm

[tex]\frac{1-\sec u}{\tan u} -\frac{\tan u}{1-\sec u}[/tex]

[tex]= \frac{(1-\sec u)^2 - \tan^2 u}{\tan u(1-\sec u)}[/tex]

[tex]= \frac{1-2\sec u+ \sec^2 u - \tan^2 u}{\tan u(1-\sec u)}[/tex]

[tex]= \frac{2-2\sec u}{\tan u(1-\sec u)}[/tex] (because [tex]\sec^2 u - \tan^2 u=1[/tex])

[tex]= \frac{2}{\tan u}[/tex]

[tex]= 2\cot u[/tex]

Hope that helped,

R. Baber.
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Re: Verify identity - need to help a student work through th

Postby Guest » Fri Nov 08, 2013 5:28 am

Thank you!
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