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+5
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avatar+466 

(2 cot x)/(tan 2x) = csc2 x - 2

I think we all know the drill... show that the left side equals the right wink

 Mar 7, 2016

Best Answer 

 #1
avatar+128475 
+10

(2 cot x)/(tan 2x) =      [tan 2x =  sin2x / cos 2x ]

 

2[cosx/sinx] / [sin2x / cos2x]     =  

 

[2*cosx*cos2x] /  [sinx * sin2x]  =

 

[2*cosx*cos2x ]  / sinx * 2sinxcosx]  =       [ 2cosx   cancels on top/bottom]

 

[cos2x]/ [ sin^2x]  =                 [  use    1 - 2sin^2 x     for cos2x ]

 

[1 - 2sin^2x] / [ sin^2x] =

 

1/sin^2x     -  2sin^2x / sin^2x  =

 

csc^2x  - 2

 

Love these, don't you Shades???  LOL!!!!

 

 

 

cool cool cool

 Mar 7, 2016
 #1
avatar+128475 
+10
Best Answer

(2 cot x)/(tan 2x) =      [tan 2x =  sin2x / cos 2x ]

 

2[cosx/sinx] / [sin2x / cos2x]     =  

 

[2*cosx*cos2x] /  [sinx * sin2x]  =

 

[2*cosx*cos2x ]  / sinx * 2sinxcosx]  =       [ 2cosx   cancels on top/bottom]

 

[cos2x]/ [ sin^2x]  =                 [  use    1 - 2sin^2 x     for cos2x ]

 

[1 - 2sin^2x] / [ sin^2x] =

 

1/sin^2x     -  2sin^2x / sin^2x  =

 

csc^2x  - 2

 

Love these, don't you Shades???  LOL!!!!

 

 

 

cool cool cool

CPhill Mar 7, 2016
 #2
avatar+466 
0

Oh yes, they're lovely. Thanks! cool

 Mar 7, 2016

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