Q3 of 186 Page 184

D and E are points on the sides AB and AC respectively of a ΔABC. In each of the following cases, determine whether DE || BC or not.

AD = 5.7 cm, DB = 9.5 cm, AE = 4.8 cm and EC = 8 cm.

Here, by applying converse of Thale’s theorem we can conclude whether or not DE ∥ BC.

By Thale’s theorem,

Solving for ,

…(i)

Solving for ,

…(ii)

As equation (i) is equal to equation (ii),

it satisfies Thale’s theorem.

Hence, we can say DE ∥ BC.

D and E are points on the sides AB and AC respectively of a ΔABC such that DE || BC.

Find the value of x, when

AD = 4 cm, DB = (x - 4) cm, AE = 8 cm and EC = (3x -19) cm.

D and E are points on the sides AB and AC respectively of a ΔABC such that DE || BC.

Find the value of x, when

AD = (7x - 4) cm, AE = (5x - 2) cm, DB = (3x + 4) cm and EC = 3x cm.

D and E are points on the sides AB and AC respectively of a ΔABC. In each of the following cases, determine whether DE || BC or not.

AB = 11.7 cm, AC = 11.2 cm, BD = 6.5 cm and AE = 4.2 cm.

D and E are points on the sides AB and AC respectively of a ΔABC. In each of the following cases, determine whether DE || BC or not.

AB = 10.8 cm, AD = 6.3 cm, AC = 9.6 cm and EC = 4 cm.

D and E are points on the sides AB and AC respectively of a ΔABC. In each of the following cases, determine whether DE || BC or not.AD = 5.7 cm, DB = 9.5 cm, AE = 4.8 cm and EC = 8 cm.