Construct an angle of measurement $22 \frac{1}{2}^{\circ}$.

(N/A) Steps of construction:
$(1)$ Draw any ray $AB$. Produce $AB$ on the side of $A$ to get line $CAB$.
$(2)$ Taking $A$ as centre and any radius,draw an arc of a circle to intersect line $CAB$ at $X$ and $Y$.
$(3)$ Taking $X$ and $Y$ as centres and radius more than $\frac{1}{2} XY$,draw arcs to intersect each other at $L$ on one side of line $CAB$. Draw ray $AL$. Then,$\angle LAB = 90^{\circ}$.
$(4)$ Draw ray $AM$,the bisector of $\angle LAB$. Then,$\angle MAB = 45^{\circ}$.
$(5)$ Draw ray $AN$,the bisector of $\angle MAB$. Then,$\angle NAB = 22 \frac{1}{2}^{\circ}$.
Thus,$\angle NAB$ is the required angle of $22 \frac{1}{2}^{\circ}$.