Draw a straight line about 20 cm long across the paper about one-third down from the top. This will be the baseline. Draw another line perpendicular to the first line using the protractor. This second line will be normal, 90°, to the first line.

The drawing is attached

Explanation:

Using your ruler, draw a straight line of 20 cm. With the middle of the line as center and any radius on your protractor, draw an arc that cuts the line in both directions (q and r).Then with the point of intersections on the line as the center of your protractor, draw two other arcs above that would intersect at point P.

Draw a line from point P to O to get your perpendicular line, 90° from the 20cm line.

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