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SAS triangle?
while solving an SAS triangle, after solving for the third side with law of cosines, why do you have to find the smallest angle (using law of sines)? i have to write a math essay thing.
i meant to say why do you have to find the smallest angle first?
1 Answer
- Anonymous1 decade agoFavorite Answer
The cosine rule enables you to find the third side when you know the angle between two known sides. Lets call this angle A. You still don't know the other two angles. All you know is that they add up to (180 - A). To work out the smallest angle, you need to first find all of the angles so you can work out the smallest.
The information you have (after finding the third side) is:
Angle A
Side a
Side b
Side c
You can therefore solve for the remaining two angles using the sine rule
a/sinA = b/sinB = c/sinC because you have the information to calculate a/sinA