ok, so with the angles we are given, its an equalateral triangle. (all angles are 60*) with this we know everything is equal to each other. so if thats the case, it should be 13
EXPLANATION: All the angles of this triangle are 60° (3rd angle= 180-60-60=60) So as it is an equilateral triangle all the sides of the triangle are same. As the length of the base is given 13 so x will also be 13.