Triangles
NCERT Exemplar Ch 06
CBSE_NCERT_EXEMPLAR_CH06
Grade 10
Question:
If in triangles $ABC$ and $DEF$, $\dfrac{AB}{DE} = \dfrac{BC}{FD}$, then they will be similar, when:
$\angle B = \angle E$
$\angle A = \angle D$
$\angle B = \angle D$
$\angle A = \angle F$
Step-by-Step Solution
Key Concept: SAS similarity requires the included angle between the two proportional sides to be equal.
Stepwise Solution:
Sides involved are $AB, BC$ in $\Delta ABC$ (included angle $\angle B$) and $DE, FD$ in $\Delta DEF$ (included angle $\angle D$). [0.5 Mark]
For SAS similarity, included angles must be equal: $\angle B = \angle D$. [0.5 Mark]
Marking Scheme:
• Identifying included angles for SAS similarity: 0.5 Mark
• Matching $\angle B = \angle D$: 0.5 Mark
Correct Answer: $\angle B = \angle D$
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