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Home » ∆ABC~∆DEF and the perimeters of ∆ABC and ∆DEF are 30cm and 18cm respectively. If BC = 9cm, then EF = ? (a) 6.3cm (b) 5.4cm (c) 7.2cm (d) 4.5cm
∆ABC~∆DEF and the perimeters of ∆ABC and ∆DEF are 30cm and 18cm respectively. If BC = 9cm, then EF = ? (a) 6.3cm (b) 5.4cm (c) 7.2cm (d) 4.5cm
CBSE | Class 10 | Exercise MCQ | Maths | RS Aggarwal | Triangles
∆ABC~∆DEF and the perimeters of ∆ABC and ∆DEF are 30cm and 18cm respectively. If BC = 9cm, then EF = ? (a) 6.3cm (b) 5.4cm (c) 7.2cm (d) 4.5cm

Correct Answer: (b) 5.4 cm

Explanation:

Given,

∆ABC ~ ∆DEF

\begin{array}{l} \frac{{Perimeter(\Delta ABC)}}{{Perimeter(\Delta DEF)}} = \frac{{BC}}{{EF}}\\ \frac{{30}}{{18}} = \frac{9}{{EF}}\\ EF = \frac{{9 \times 18}}{{30}}\\ EF = 5.4cm \end{array}

i

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