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(tanx + 1)^2 cosx

 

answer: secx +2sinx 

how? please & thanks

Guest Apr 26, 2017
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(tanx + 1)^2 cosx          expand

 

(tan^2x + 2tanx + 1) cosx

 

(tan^2x + 1  + 2tanx) cos x      re-order inside the parentheses

 

........... tan^2x + 1   = sec^2x ..........

 

(sec^2x + 2tanx) cosx          put everything in terms of sine, cosine        

 

( 1/cos^2x   +  2 sinx / cos x )  cosx        

 

 Distribute the cosx acroos the terms in the parentheses

 

( 1/cos x  +  2 sin x)

 

secx  + 2sinx

 

 

cool cool cool

CPhill  Apr 26, 2017

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