Level 4: Construct a line (segment) that goes through point A perpendicular to the given line segment

Hint: Make some new point to unblock. Diagonal of rhombus are perpendicular to each other.

Solution: Given the hint, all we need to do is do redo the rhombus trick in level 2. But there is just one point? No worries, just create one using the point of the object tool. We just pick point D somewhere, to make A the midpoint, I used the circle tool to construct a circle with center A and radius AD. Mark the two intersections as E and F, and A is obviously the midpoint of EF. To complete the construction, note that we already know A is the intersection point between the diagonals, so we only need one equilateral triangle and join the vertex to A, and we are done.