## Precalculus (6th Edition)

In order to solve a triangle at least 3 unknown quantities must be given 1) one side and two angles 2) one angle and two sides 3) three sides But when its given only three angles we cannot solve triangle because when two angles of triangle are given we can find third angle easily because sum of internal angles of triangle is $180^0$ so third angle will not be unknown So in this case we have sufficient information to solve the triangle.