How to find an angle knowing the coordinates of a point?

Question

Mathematics

There is a circle and there are coordinates of points x and y lying on it. How to calculate angle in degrees?

Answer 1

If the center of the circle is (0, 0), then the tangent of the angle (from the OX axis) to each point is y/x. Take the arc tangent - you get the first angle, likewise the second angle. Subtract one angle from the other.
If the center of the circle is not (0, 0), then translate to another coordinate system so that it is (0, 0).

Answer 2

Construct an equilateral triangle, the base of which is the chord between the points, and the opposite vertex is the center of the circle. Build the height of the triangle, you get two equal right triangles. The rest is the simplest school trigonometric problem.