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(a) Determine the Quadrant in which (U/2) lies 

(b) find the exact values of sin(u/2), cos(u/2) and tan (u/2)

 

cot(u)= -1/3, 3pi/2 <U< 2Pi

 Nov 22, 2016
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(a) Determine the Quadrant in which (U/2) lies 

(b) find the exact values of sin(u/2), cos(u/2) and tan (u/2)

 

cot(u)= -1/3, 3pi/2 <U< 2Pi..........then u/2 will fall into the 2nd quadrant

 

If the cotangent is -1/3, then  r = √[!1^2 + 3^2]  = √10

 

And the sin of u  = -3/√10      and the cos of  u  =   1/√10

 

So.....

 

tan (u/2) =  sin u / [ 1 + cos u]  = [ -3/√10] / [ 1 + 1√10] =   [-3√10] / [  (√10 + 1) / √10]  =  [-3] / [  √10 + 1]

 

And

 

sin (u/2) =  √ [(1 - cos u) / 2]  = √ [(1 - 1/√10)/ 2 ]   = √ [ (√10 - 1) / (2√10)] 

 

cos(u/2)  = -√ [ (1 + cos u) / 2 ]  = -√ [  [(1 + 1/√10)/ 2 ]  =  - √ [(√10 + 1) / (2√10)]

 

 

 

cool cool cool

 Nov 22, 2016

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