Question

draw a line of a b of length 7.3 cm and find its axis of symmetry

Answer 1

by taking more than half of 7.3cm.
draw perpendicular bisector.
therefore join the line of symmtery

Answer 2

A__________________.__________________B
the point which i have made is the axis of symmetry
the line AB  7.3 cm long
(7.3/2 )= 3.65 cm 
i hope that it will help you a loy