First of all we draw a rough sketch of the given measurements :
Steps of Construction
(i) First of all we draw a line segment AB = 8 cm.
(ii) At point A construct ∠BAX = 90° with AB.
(iii) From AX cut AD = 6 cm., an arc of 6.0 cm is cut on AX and marked a point D.
(iv) Similarly at point B draw ∠ABY = 90° with AB and cut BC = 6 cm from ray BY.
(v) Join CD.
Thus, we obtained required rectangle ABCD.