Geometry

[woeful yacht]

#1015578016606343218

[tight harness]

(a).
Note that the angle between AC and CT must be 90°, as CT is a tangent and AC is the diameter.
(b).
Two tangents drawn from one point have the same length. Thus, the triangle TBC is isosceles.

[woeful yacht]

So Y is 56?

[tight harness]

Yes.

[woeful yacht]

Thanks you so much

[hoary depot]

@woeful yacht has given 1 rep to @tight harness

[tight harness]

You're welcome!

[woeful yacht]

And X=28 ?

[tight harness]

Yes.

[woeful yacht]

Thank you sm for helping!