Omar is constructing a square inscribed in a circle. he begins by constructing a circle with a center o and with a diameter connecting points a and c .

what is omar's next step in the construction?

a
starting at point a , use the compass with a setting of the length of the radius to mark off the radius four times around the circle.

b
use oa to construct a line tangent to the circle at point a .

c
construct a perpendicular bisector of ac , making it long enough to touch the circle above and below the diameter.

d
construct a perpendicular bisector of oc , making it long enough to touch the circle above and below the diameter.