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http://prntscr.com/lfjdea

 Nov 7, 2018
 #1
avatar+100586 
+1

We know that   x  = 8  and y = -7

 

r  =  sqrt  [  (8^2   + (-7)^2 ]   =   sqrt [ 64 + 49]  =  sqrt [ 113]

 

So.....cos (theta)   =  x / r   =   8 / sqrt (113)

 

Multiply both numerator and denominator by  sqrt [ 113]   and we have

 

8 sqrt (113)                             8sqrt (113)

_________________ =         __________

sqrt(113) * sqrt (113)                 113

 

 

cool cool cool

 Nov 7, 2018

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