In triangle $ABC$, $a=13\sqrt{3}$, $b=13$, $\angle B=30^{\circ}$, and $\angle C$是严重的。的值是多少 $\angle C$(in degrees)?

Details and assumptions

$a$, $b$and $c$are the lengths of the sides opposite to the vertices $A$, $B$and $C$, respectively. An acute angle is an angle strictly less than $90^\circ$.