Answers

2016-05-22T23:43:01+08:00
My answer is in the picture below.



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2016-05-23T17:06:10+08:00
    cos(x+30°)cos(x-30°)  = 1/2
     as this is an equation you must find the value of x that will make the            equation true
      by inspection or common sense you can deduce that  x   =   30°
      
     ie    cos 60°cos 0°    =   1/2        /    cos 60 = 1/2 ,    cos 0   = 1
            
           so       1/2    = 1/2     true
            
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