11*. From a point $M$ on the edge of a dihedral angle in one of its faces, a ray is drawn. Draw from the same point $M$ in the other face a ray that forms an angle of a given magnitude with the first ray.
11. Let's take an arbitrary point $A$ on this ray; let $A^{\prime}$ be the projection of this point onto the other face. Suppose the desired ray is drawn, and we construct a segment $M B$ on it such that $|M B|=|M A|$. Then, in the isosceles triangle $A M B$, the two sides and the angle between them are known, and it can be constructed on a separate drawing. We will then know the length of the slant $|A B|$, and consequently, the length of its projection $\left|A^{\prime} B\right|$ onto the second face. The desired point $B$ must lie on the circle with center at point $A^{\prime}$ and radius $\left|A^{\prime} B\right|$, and at the same time on the circle with center at point $M$ and radius $|M A|$. By constructing point $B$, we will determine the desired ray. Determine how many solutions the problem can have.

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