$-a,0x^2+y^2=a^2$

$a.$ once clockwise.

$b.$ once counterclockwise.

$c.$ two times clockwise.

$d.$ two times counterclockwise.

$a.$ Which $of$ the following sets $of$ equations could trace the circle $x^2+y^2=a^2$ once clockwise, starting $at(-a,0)?$

$A.x=$acost,$y=-$asint,$0t2$

$B.x=-$asint,$y=-$acost,$0t2$

$C.x=-$acost,$y=$asint,$0t2$

$D.x=$asint,$y=$acost,$0t2$

$b.$ Which $of$ the following sets $of$ equations could trace the circle $x^2+y^2=a^2$ once counterclockwise, starting $at(-a,0)?$

$A.x=-$acost,$y=-$asint,$0t2$

$B.x=$acost,$y=$asint,$0t2$

$C.x=$asint,$y=-$acost,$0t2$

$D.x=-$asint,$y=$acost,$0t2$

$c.$ Which $of$ the following sets $of$ equations could trace the circle $x^2+y^2=a^2$ two times clockwise, starting $at(-a,0)?$

$A.x=$acost,$y=-$asint,$0t6$

$B.x=-$acost,$y=$asint,$0t4$

$C.x=-$asint,$y=-$acost,$0t8$

$D.x=-$acost,$y=$asint,$0t2$

$d.$ Which $of$ the following sets $of$ equations could trace the circle $x^2+y^2=a^2$ two times counterclockwise, starting $at(-a,0)?$

$A.x=-$acost,$y=-$asint,$0t2$

$B.x=-$acost,$y=-$asint,$0t4$

$C.x=$asint,$y=-$acost,$0t8$

$D.x=$acost,$y=$asint,$0t6$