What is the first step in the constitution of a line perpendicular to ab and passing through an external point m?

take your compass on a point on your line. then draw a circle. take the 2 points in which the circle hit the line and draw 2 circles larger than half the distance between he 2 points. take the point that they intersect and and connect it to the line and you point M and it is purpendicular. does that make sense?

step-by-step explanation:

in which figure is point g a centroid