It depends. If the vertex of the angle is at the center of the circle it is 80° by the arc angle postulate, meaning the measure of an angle with a vertex at the center of the circle is always equal to it's arc. If the vertex of the angle is on the outer edge of the circle it is 40° by the arc edge postulate, meaning the measure of an angle with a vertexat lying on the outer edge is exactly 1/2 the measure of the arc! hope I helped you learn! brainliest would be much appreciated!!
