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How can you find the angles of a triangle if you have all the sides?

 Jan 19, 2017

Best Answer 

 #4
avatar+26376 
+60

How can you find the angles of a triangle if you have all the sides?

 

\(\begin{array}{|rcll|} \hline \cos{(B)} &=& \frac{1}{2c}\cdot \left(a+\frac{c^2-b^2}{a} \right) \\ \cos{(C)} &=& \frac{1}{2b}\cdot \left(a-\frac{c^2-b^2}{a} \right) \\ A &=& 180^{\circ}-(B+C) \\ \hline \end{array}\)

 

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 Jan 20, 2017
 #1
avatar+36919 
0

Using law of sines   and law of cosines     yes

 Jan 19, 2017
 #2
avatar+502 
+5

You can use the Cosine rule which is

CosA= c+ b2- a2/ 2bc 

and the same with B and C

 Jan 19, 2017
 #3
avatar+23247 
+5

If the angles of the triangle are A, B, and C with the opposite sides a, b, and c,

then  C  =  cos-1(  (a2 + b2 - c2) / (2·a·b)  ).

Similar formulas for the other angles.

 Jan 19, 2017
 #4
avatar+26376 
+60
Best Answer

How can you find the angles of a triangle if you have all the sides?

 

\(\begin{array}{|rcll|} \hline \cos{(B)} &=& \frac{1}{2c}\cdot \left(a+\frac{c^2-b^2}{a} \right) \\ \cos{(C)} &=& \frac{1}{2b}\cdot \left(a-\frac{c^2-b^2}{a} \right) \\ A &=& 180^{\circ}-(B+C) \\ \hline \end{array}\)

 

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heureka Jan 20, 2017

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