Point O is the center of the circle. It is known that the angle ABC = 71 degrees

Point O is the center of the circle. It is known that the angle ABC = 71 degrees and the angle OAB = 39 degrees Find the angle BCO

Consider a triangle OAB – isosceles (OA, OB – radii).
The angles at the base AB are equal, we get:
∠ ABO = ∠ OAB = 39 °.
We find the degree measure of the OBC angle:
∠ OBC = ∠ ABC – ∠ ABO = 71 ° – 39 ° = 32 °.
Consider an isosceles triangle ОВС (ОВ, OC – radii).
∠ ВСО = ∠ ОВС = 32 ° (angles at the base of an isosceles triangle).
Answer: the degree measure of the angle BCO is 32 °.