given that Given that DEAC BD 2 cm DA 5 cm and BE 3 cm fi

given that...........

Given that DE//AC, BD = 2 cm, DA = 5 cm, and BE = 3 cm, find the length of BC.

Solution

In the ^s BAC and BDE, DE is parallel to AC, and B is common to both. Therefore, the ^s BAC and BDE are similar triangles. Hence BD/BA = BE/BC or, 2/(2+5) = 3/BC or, BC = 3*7/2 = 21/2 = 10.5 cm.