The union of a chord of a circle and its corresponding arc is called $\ldots \ldots \ldots \ldots$

In a circle with radius $6.3 \ cm$,an arc subtends an angle of measure $150^{\circ}$ at the centre. Find the length of this arc and the area of the sector formed by this arc.

The circumference of a circle is $176\,cm$. Then,its radius is $\ldots \ldots \ldots \ldots cm$.

In $\odot(O, 4)$,$\widehat{ACB}$ is a minor arc and $m \angle AOB = 45^\circ$. Then,the length of minor $\widehat{ACB}$ is $\ldots \ldots \ldots \ldots$

The circumference of a circle is $176 \, cm$. Find its radius in $cm$.

As shown in the diagram,the side length of square $ABCD$ is $35 \, cm$. Two semicircles are drawn on its sides $\overline{AB}$ and $\overline{CD}$ as diameters. Find the area of the shaded region in $cm^2$.