13. Non-Right Triangles

A surveyor wishes to find the distance across a river while standing on a small island. If she measures distances of $a=30m$ to one shore, $c=60m$ to the opposite shore, and an angle of $B=100\degree$ between the two shores, find the distance between the two shores.

Use the Law of Cosines to find the angle $C$, rounded to the nearest tenth.



Solve the triangle: $b=5,c=3,A=100\degree$.

Solve the triangle: $a=5$, $b=15$, $c=13$.