Question

What is the the length of c?

Answer 1

A thousand ways you could solve this, but generally need to understand 3 concepts to do so

1. interior angles of triangle add up to 180 degrees
2. law of sines
$\frac{a}{sin A}=\frac{b}{sin B}= \frac{c}{sinC}$
3. law of cosines
$c^2= a^2+b^2 -2ab* cos(C)$

my personal suggestion

determine what angle A is, then use law of sines in order to determine side c