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Secondary Level Questions
How do you solve this? Do you solve this triangle using the law of sines of the law of cosines? (ASA)
 A=120DEG.     B=40DEG    c=35 cm
I keep getting different answers.


Hi Joy,

To use the law of cosines you need to know the lengths of two sides.

Since the sum of the angles in a triangle is 180 degrees you know that the measure of angle C is 20 degrees. Thus



a = c sin(A)/sin(C)35 sin(120)/sin(20) =  35 0.866025/0.34202 = 88.62 cm

Now do the same to solve for b. I got b = 65.78 cm.



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