[wolfgang]

If you have a piece of ruler( without graduations)which is 26 cm long.

How can you draw a 29 cm long striaght line on a white paper using this ruler only?

you are not allowed to break the ruler or cut any piece of the paper, the paper is irregular in shape but lagre enough.

(near to 29 is acceptable)...i.e. the difference should be < 0.1

[Guest]

Draw a 26 CM line. Now fold the paper such that two ends of the line meet together. This will mark a perpendicular bisector of the line. Starting at the midpoint of this line, draw another 26 cm line along the perpendicular bisector. Complete a right angle triangle with one side as 26cm (2nd line) and another as 13cm (any half of first line). The hypotenuse is of 29.06 cm.

[wolfgang]

Draw a 26 CM line. Now fold the paper such that two ends of the line meet together. This will mark a perpendicular bisector of the line. Starting at the midpoint of this line, draw another 26 cm line along the perpendicular bisector. Complete a right angle triangle with one side as 26cm (2nd line) and another as 13cm (any half of first line). The hypotenuse is of 29.06 cm.

Great...!!

[Guest]

i think that it is logical that pen is to b taken as given in dis situation. even if not , one can use ones nail or rulers edge to draw a line. well the riddle is easy : mark the initial point and then use the 26cm ruler thrice to make a point at a distance of 78 cm. then get hte middle point of these 2 lines by folding the paper . from either points the middle point is 29 cm long . now we can draw it with a pen or nail.

Isn't that supposed to be 39 cm?

[Guest]

But how can you be sure if that's an exact 13cm length if u only visually divide it?