Explanation:
Solving a triangle means finding all unknown sides and angles.
For example, in #9, the third angle is 180° − 81° − 59° = 40°.
Using law of sines, the other two sides are:
a / sin 59° = 15 / sin 40°
a = 20.0
b / sin 81° = 15 / sin 40°
b = 23.0