Can you please help with the inscribed angle theorem? I have this theorem in my textbook

The angle subtended at the centre by an arc of a circle is double the
angle which this arc subtended at any point on the remaining part of
the circle.

Now consider this diagram

Now if we go my the above theorem the yellow angle must be equal to 'x'(which is half the angle subtended at the center).
But it is not the case.Why so?
 A: "On the remaining part of the circle" means not on the arc that was mentioned in the first part of the theorem.
The radii drawn in red divide the circle into two arcs.
Arc $A$ is the short arc that sits inside the angle marked $2x$ and is the "arc of a circle" that subtends the angle $2x$ at the center of the circle.
Arc $B$ is the long arc that goes around the top of the circle from one end of the short arc to the other. Part B is "the remaining part of the circle".
From any point on arc $B,$ arc $A$ subtends an angle $x.$
On the other hand, you could take arc $B$ as the "arc of a circle"
and take arc $A$ as the "remaining part",
in which case you find that arc $B$ subtends the angle
$2\pi - 2x$ (that is, $360^\circ - 2x$)
and the yellow angle on arc $A$ is half that angle.
A: The yellow $\bbox[black, 5px]{\color{yellow}x}$ is half of the reflex $\angle O = 360^\circ - 2x$. i.e.
$$\bbox[black, 5px]{\color{yellow}x} = 180^\circ - x$$

Imagine standing at where the blue lines meet (or anywhere on the minor arc), the angle of view of the major arc is $\bbox[black, 5px]{\color{yellow}x}$.
And imagine standing at $O$. The angle of view of the major arc is not $2x$, but the reflex angle $360^\circ - 2x$. (And you have to turn to see the full major arc) Then the theorem says
$$360^\circ - 2x = 2\ \bbox[black, 5px]{\color{yellow}x}$$
A: The yellow angle does not intercept the same arc as the angle at centre. It intercepts the circle minus this arc, i.e. $2(\pi -x)R$, if $R$ is the radius of the circle.
