SOLUTION: given a triangle with sides 4, 5, 6. find the EXACT values of the angles to show that one angle is EXACTLY twice the other (no estimations).
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Question 275040:  given a triangle with sides 4, 5, 6. find the EXACT values of the angles to show that one angle is EXACTLY twice the other (no estimations). 
Answer by kensson(21)   (Show Source): You can put this solution on YOUR website!
 Interesting!
The cosine rule is: 
Or, rearranging, 
So the cosine of the angle opposite the 4 side is  = 45/60 = 3/4.
Opposite the 5:  = 27/48 = 9/16.
Opposite the 6:  = 5/40 = 1/8.
So the smallest angle is arccos(3/4), the middle angle is arccos(9/16) and the biggest angle arccos(1/8).
Now, . For the smallest angle:
So the largest angle is twice the size of the smallest one.
 
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