Answer:

Step-by-step explanation:
Givens
- AC and BD are diameters.
- Angle BCA measures 53°.
Notice that line segment BE is congruent to line segment CE, because they are the radius of the circumference. That means the triangle that contains these sides is isosceles.
, by definition of triangles isosceles.
Then,
, by sum of internal angles.
And,
, by vertical angles definition.

But, we know that the measured of a subtended arc is equal to its angle.
Therefore, 