$1\mathrm{.}5.$ A mechanism for controlling the opening of an awning window is shown in Fig. Pl$\mathrm{.}4.$ The ver$-$

tical member is fixed to the frame of the house. The link with the label on it carries the window.

The mechanism causes the window to move straight out from the building $($clearing the metal

lip around the window$)$ before rotating the window out in a counterclockwise direction.

$($a$)$ What task does this mechanism satisfy?

$($b$)$ Calculate the degrees of freedom of this mechanism.

$($c$)$ Which type of six$-$bar is used here?