- ✓$D E=12 cm, \angle F=100^{\circ}$
- B$D E=12 cm, \angle F=50^{\circ}$
- C$EF =12 cm, \angle D =30^{\circ}$
- D$EF =12 cm, \angle D =100^{\circ}$
$\angle A =30^{\circ}, \angle C =50^{\circ}, AB =5 cm, AC =8 cm$ and $DF =7.5 cm$

$\angle B=180^{\circ}-(\angle A+\angle C)(\because \text { Linear pair })$
$=180^{\circ}-\left(30^{\circ}+50^{\circ}\right)$
$\angle B=180^{\circ}-80=100^{\circ}$
$\because \triangle A B C \sim \triangle D F E$
$\therefore \angle D =30^{\circ}, \angle B =\angle F =100^{\circ}$
और $\angle C=\angle E=50^{\circ}$
और $\frac{A B}{D F}=\frac{A C}{D E}=\frac{B C}{E F}$
$\frac{5}{7.5}=\frac{8}{ DE } \Rightarrow DE =\frac{8 \times 7.5}{5}=12.0=12 cm$
$\therefore DE =12, \sqrt{F}=100^{\circ}$





