Label the three location points A, B and C. Draw lines that connect A to B and B to C.
Use the scale key to discover how many miles are between points A and B by measuring the scale diagram and superimposing that measurement onto the space between the two points. For instance, if your city and your friend's city are 1 inch apart on the map and your map's scale is 1 inch to 20 miles, this means that your two cities are 20 miles apart.
Determine the midpoint between points A and B by dividing the distance between them in half. Mark that midpoint. Draw a perpendicular line through the segment's midpoint. Repeat the process for the segment that runs between B and C.
Settle the compass's needle at the point where the two perpendicular bisectors meet. Widen the hinge until the pencil rests on one of the location points. Tighten the hinge and twist the knob until all three points are intersected by the circle's circumference.
Meet at the midpoint of the circle.
