Answer:
The length of the line GA would be 13
Explanation:
G is the circumcenter (where the perpendicular bisectors of a triangle intercept) of the triangle. The line GA is one of those perpendicular bisectors. The two dashes on the sides of the triangles show that they are all equivalent on that side. The two squares show that they art right triangles. This means the lines GB and GA are equivalent. So if GB=13, then GA=13.