SOLUTION: A triangle has sides a = 6, c = 8, and angle B = 125° Determine angle A.

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Question 977350: A triangle has sides a = 6, c = 8, and angle B = 125° Determine angle A.
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Hi there,
First, you should find out what
b =.
Using Cosine Rule
b^2 = a^2 + c^2 - 2ac CosB
b^2 = 36 + 64 -(2 * 6 * 8 * cos 125)
b^2 = 100 - (-55.0633)
b^2 = 155.0633
b = square root of 155.0633
b = 12.5 (1 decimal place)
Now using Sine Rule
a/SinA = b/SinB
6/SinA = 12.5/sin125
Cross multiply
6 * sin125 = 12.5sinA
SinA = 6*sin125/12.5
SinA = 0.3932
Sin^-1A = 23.2 degrees (i decimal place)
Hope this helps:-)