Exercise $4.$ Assume a clockwise winding order. Calculate the normalized normal vector for the

triangle rendered by the following code segment, assuming that OpenGL uses a left$-$hand

coordinate system where the x$-$axis extends to the right and the y$-$axis extends upward.

glBegin$($GL$\_$TRIANGLE$\_$FAN$)$;

glVertex$2$f$(0.,0\mathrm{.}5)$;

glVertex$2$f$(0\mathrm{.}2,0\mathrm{.}5)$;

glVertex$2$f$(0\mathrm{.}4,0\mathrm{.}5)$;

glVertex$2$f$(0\mathrm{.}6,0\mathrm{.}9)$;

glVertex$2$f$(0\mathrm{.}7,0\mathrm{.}2)$; glVertex$2$f$(0,$

$-0\mathrm{.}2)$; glVertex$2$f$(-0\mathrm{.}2,0\mathrm{.}0)$;

glEnd$()$;

glBegin$($GL$\_$TRIANGLES$)$;

for $($int i $=1$; i $<10$; $++$i$)\{$ glVertex$2$f$(0\mathrm{.}09*$i$,-0\mathrm{.}7)$;

glVertex$2$f$(-0\mathrm{.}09*$i$,-0\mathrm{.}3)$;

$\}$ glEnd$()$;

glBegin$($GL$\_$TRIANGLE$\_$FAN$)$;

glVertex$2$f$(0\mathrm{.}4,0\mathrm{.}4)$; glVertex$2$f$(-0\mathrm{.}3,0\mathrm{.}2)$;

glVertex$2$f$(0\mathrm{.}2,-0\mathrm{.}3)$;

glEnd$()$;