i. Draw three parallel lines.
ii. Label them as l, m, n.
iii. Draw transversals t1 and t2.
iv. AB and BC are intercepts on transversal t1.
v. PQ and QR are intercepts on transversal t2.
vi. Find ratios AB/BC and PQ/QR. You will find that they are almost equal. Verify that they are equal.