Question
In the given figure, $\triangle\text{OAB}\sim\triangle\text{OCD}.$ If AB = 8cm, BO = 6.4cm, OC = 3.5cm and CD = 5cm, find.
  1. OA
  2. DO

Answer

  1. Let OA be x cm.
$\therefore\triangle\text{OAB}\sim\triangle\text{OCD}$

$\therefore\frac{\text{OA}}{\text{OC}}=\frac{\text{AB}}{\text{CD}}$

$\Rightarrow\frac{\text{x}}{\text{3.5}}=\frac{\text{8}}{\text{5}}$ and

$\Rightarrow\text{x}=\frac{8\times3.5}{5}=5.6$

hence, OA = 5.6cm
  1. Let OD be y cm
$\therefore\triangle\text{OAB}\sim\triangle\text{OCD}$

$\therefore\frac{\text{AB}}{\text{CD}}=\frac{\text{OB}}{\text{OD}}$

$\Rightarrow\frac{\text{8}}{\text{5}}=\frac{\text{6.4}}{\text{y}}$

$\Rightarrow\text{y}=\frac{6.4\times5}{8}=4$

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