Draw a line AB.

Draw a line segment AB.

Draw the midpoint I of the line segment AB.

The circle intersects this line at D and C.

It intersects the circle at E and F.

Draw the circle with centre I and diameter AB.

Draw the line parallel to the line DB through the point I.

Draw the line perpendicular to the line DB through the point I.

Draw line the perpendicular to the line AB through the point I.