How do you determine the number of possible solutions using the rule of law of sines given b=15.2, A=12°30', C=57°30'?

1 Answer
Jul 10, 2015

Solve triangle knowing b, A, and C

Explanation:

Find B, a and c.
Angle B = 180 - C - A = 180 - 57.30 - 12.30 =110.40 deg
Use trig identity: asinA=bsinB

a=b(sinBsinA)=15.2(0.940.21)=68.04,

There are 2 possible solutions, because 0.94 is the same sin value of 2 angles: B = 110.40 and B = 69.60. However, the solution angle B = 69.60 is rejected, because the sum A + B + C must be 180 deg.

c=b(sinBsinC)=15.2(0.940.84)=17.00