This construction constructs the square root of a segment AB. (The points in between show that segement AB is nine units long).

1. Draw the segment AB.

2. Extend line AB.

3. Draw segment AC on line AB with a length equal to "1" (AB = 9, so divide it into nine to find the length of AC).

4. Bisect segment CB and draw a circle about it with a radius to C or B.

5. Construct a perpendicular at A to CB intersecting the circle in two points (one shown).

6. Call the point of intersection D.

7. AD equals "3", the square root of "9". (The small green circles are of a unit radius, and so show this.).

You can also use another method of constructing square root. Square Root 2.

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