Steps of construction:
(i) Draw a line 'l' and take a point X on it.
(ii) Construct ¯¯¯¯¯¯¯¯¯XZ such that length ¯¯¯¯¯¯¯¯¯XZ = length of ¯¯¯¯¯¯¯¯AB = 7.3 cm
(iii) Then cut off ¯¯¯¯¯¯¯¯ZY = length of ¯¯¯¯¯¯¯¯¯CD = 3.4 cm
(iv) Thus the length of ¯¯¯¯¯¯¯¯¯XY = length of ¯¯¯¯¯¯¯¯AB – length of ¯¯¯¯¯¯¯¯¯CD
Verification:
Hence, by measurement we find that length of ¯¯¯¯¯¯¯¯¯XY = 3.9 cm
= 7.3 cm – 3.4 cm
= ¯¯¯¯¯¯¯¯AB - ¯¯¯¯¯¯¯¯¯CD