Please consider the attached graph of circle O.
We have been given that angle C is inscribed in circle O. AB is diameter of circle O. We are asked to find the measure of angle B.
We can see that angle C is inscribed angle of diameter AB. We know that an inscribed angle whose endpoints are a diameter is a right angle. So measure of angle C will be 90 degrees.
We also know that all angles of a triangle add up-to 180 degrees, so we can set an equation as:





Therefore, the measure of angle B is 44 degrees.