Answer:
Step-by-step explanation:
Remark
This is a cosine law problem.
a = 12
b = 15
C = 83
Notice that the angle is enclosed by 2 given sides. That's what a cosine problem looks like (one of the two choices.
Formula
c^2 = a^2 + b^2 - 2ab*cos(C)
Solution
c^2 = 12^2 + 15^2 - 2*12*15 * cos(83)
c^2 = 144 + 225 - 360 * cos(83)
cos(83) = 0.1219
c^2 = 144 + 225 - 360 * 0.1219
c^2 = 369 - 43.884
c^2 = 325.116
sqrt(c^2) = sqrt(325.116)
c = 18.031
To the nearest tenth, the answer is 18.0 and you must include the 0.
