Given 2 points how do I draw a line at a right angle to the line formed by the two points?

Question

Idealy I want to supply a sequence of points and have a line drawn at a right angle at every point (starting at the second point). The direction of each line would alternate, so if I happened to draw a curve cosisting of 6 points, a line of a given lenth would be drawn for each point starting with the second point, i.e 5 additional lines on alternating sides of the curve, a bit like a caterpillar with alternating legs. (I understand that the lines won't be entirely at right angles to the curve but rather at right angle to the line formed by any two points on the curve).

Answer 1

Please check my re-wording. "Draw perpendicular line segments on alternating sides of given line segments at the endpoint of each given line segment."

Whether the endpoints are "on a curve" or not is not relevant. How many points is not relevant.

A perpendicular line has a slope that is the negative reciprocal of a given line [or line segment].

Graphically, the purpose of a protractor is to indicate angles.

So. Method 1: Use a Protractor is pretty simple.

Method 2: Use a Compass: Connect the dots to form the given line segment. Set a drawing compass to that line segment length. Move the compass to the other endpoint and draw an arc that crosses the extended line segment. Now, the method of bisecting a line segment applies.

To bisect a line segment. Make the distance of the compass longer than half of the line segment and draw an small arc on each side of the line segment. Using the same compass setting, place the point on the other end of the line segment and draw arcs that intersect these two arcs. This creates two points on the perpendicular line. Draw a line or line segment using these two points.

Answer 2

Let (x,y) and (a,b) be the two points

To find the slope between them use the formula for slope, m = (y-b)/(x-a).

The slope of the line that is perpendicular to the line between (x,y) and (a,b) is -1/m = -(x-a)/(y-b).

The slope is rise over run, so if the slope is 3/4, go up 3 and right 4.

If the slope is -3/4, then go down 3 and right 4.

If the slope is a number like 4, go up 4 and right 1, since 4=4/1.