Q4.    Given \overline{AB} of length 3.9 cm, construct \overline{PQ} such that the length of \overline{PQ} is twice that of \overline{AB}. Verify by measurement.


(Hint: Construct \overline{PX} such that length of \overline{PX} = length of \overline{AB} ; then cut off \overline{XQ} such that \overline{XQ} also has the length of \overline{AB} .)

Answers (1)
D Divya Prakash Singh

The steps of constructions are following:

(i) Draw a line ′l′.

(ii) Construct \bar{PX} such that length of \bar{PX} = length of \bar{AB}

(iii) Then cut of \bar{XQ} such that \bar{XQ} also has the length of \bar{AB} .

(iv) Thus the length of \bar{PX}  and the length of \bar{XQ} added together make twice the length of \bar{AB}.


By measurement we find that PQ = 7.8 cm

= 3.9 cm + 3.9 cm = \bar{AB} + \bar{AB}   = 2\times\bar{AB} .