D and E are points on the sides AB and AC respectively of a ∆ABC such that DE║BC. (i) If AD = 3.6cm, AB = 10cm and AE = 4.5cm, find EC and AC. (ii) If AB = 13.3cm, AC = 11.9cm and EC = 5.1cm, find AD.

contexto.130

3 years ago

(i)

In ∆ ABC,

DE ∥ BC.

Applying Thales’ theorem,

∵ AD = 3.6 cm , AB = 10 cm, AE = 4.5cm

∴ DB = 10 − 3.6 = 6.4cm

(ii)

In ∆ ABC,

DE || BC

Applying Thales’ Theorem,

Add 1 to both sides,