Question

In figure below (i) and (ii), DE || BC. Find EC in (i) and AD in (ii).
(i)
(ii)

Answer 1

(i)
Let EC = x cm
It is given that DE || BC.
By using basic proportionality theorem, we obtain
$\frac{AD}{DB}=\frac{AE}{EC}$
$\frac{1.5}{3}=\frac{1}{x}$
$x=3\times \frac{1}{1.5}$
x=2
∴ EC= 2 cm

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(ii)
Let AD = x cm
It is given that DE || BC.
By using the basic proportionality theorem, we obtain
$\frac{AD}{DB}=\frac{AE}{EC}$
$\frac{x}{7.2}=\frac{1.8}{5.4}$
x=$\frac{1.8\times 7.2}{5.4}$
x=2.4
∴ AD= 2.4 cm