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+1
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https://vle.mathswatch.co.uk/images/questions/question15442.png

lynx7  Feb 11, 2018
 #1
avatar+86935 
+2

a. cos (60)  =   1/2

 

b. Using the Law of Cosines

 

b^2  =  8^2  + 5^2  -   2 (8) (5) cos (1/2)

 

b^2  =  64 + 25  - 80 (1/2)

 

b^2   =  89  -  40

 

b ^2  =  49       take the positive root

 

b  = 7

 

 

cool cool cool

CPhill  Feb 11, 2018

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