In Fig. 4.240, in such that BC = 8 cm, AB = 6 cm and DA =1.5 cm. Find DE.


Given DE || BC, BC = 8 cm, AB = 6 cm and DA = 1.5 cm.


So, PR = 6 cm.


In ΔABC and ΔADE,


ABC = ADE [corresponding angles]


ACB = AED [corresponding angles]


A = A [common angle]


We know that AAA similarity criterion states that in two triangles, if corresponding angles are equal, then their corresponding sides are in the same ratio and hence the two triangles are similar.


ΔABC ~ ΔADE


We know that two triangles are similar if their corresponding sides are proportional.




DE = 2 cm


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