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1. What is the measure of A, to the nearest degree? 

Options: 17, 33, 57, 73 dg

 

2. What is the measure of E,rounded to the nearest degree?

Options: 28, 36, 54, 80 dg

 

3. A triangle has sides lengths 5 ft, 9 ft, and 13 ft. What is the measure of the angle opposite the side that is 9 ft long? Round to the nearest degree. 

Options:30, 41, 60, 87 dg

Guest Apr 14, 2017
 #1
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Both of these can be solved by manipulating the Law of Cosines  as follows :

 

arccos [ (a^2 - b^2 - c^2) / [ -2(b)(c)] = A  

 

Where  "a" is the side opposite the angle we are trying to find [Angle "A"] and "b" and "c" are the other two sides

 

For the first, we have that

 

arccos  [ ( 4^2 - 7^2 - 7^2) / [ -2(7)(7)]   = A  ≈  33.2°  = 33°

 

 

For the secomd, we have

 

arccos  [ ( 6^2 - 7^2 - 10^2) / [ -2(7)(10)]   = E  ≈  36.18°   =  36° 

 

Based on these....see if you can do the last one....if you get stuck.....let us know.....

 

 

 

cool cool cool

CPhill  Apr 14, 2017

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