Answer:
84°
Step-by-step explanation:
The central angle of a circle is twice any inscribed angle subtended by the same arc.
because AB is a diameter, we also know that the triangle angle at C is 90° (all the inscribed triangles with their baseline being a diameter are right-angled).
as always, the sum of all angles in a triangle is 180°.
so, we know the triangle angle at A is
180 - 90 - 48 = 42°.
this is also the inscribed angle of the arc BC.
the central angle for arc BC (that is what is requested here) is then twice that angle : 2×42 = 84°
