Any measure you like. The shape has not been specified properly.
If your "53" is in degrees, then the vertex angle is 74 degrees.
Vertex angle = 180 - 2(62) = 56 degrees
If that '56' has units of 'degrees', then the vertex angle is 68 degrees.
Vertex angle is 180-53-53 = 74 degrees
You require another piece of information. Knowing the "vertex" angle will not tell you the length of any one side. You can have a triangle the size of the continental USA with a "vertex" angle of 15 degrees and you can have a triangle invisible to the human eye with a "vertex" angle of 15 degrees. You can see how these would have different side lengths.
If the 58Â°-angle is one of the base angles, then the vertex angle is 64Â°.If the 58Â°-angle is the vertex angle, then the vertex angle is 58Â°.
The third angle of what shape?
90 degrees. This is an isosceles right triangle, standing on its hypotenuse.