In the figure, if DE∥ BC, AD = 3cm, BD = 4 cm and BC = 14 cm, then DE equals

(a) 7 cm    (b) 6 cm     (c) 4 cm      (d) 3 cm

 

This question is inspired from Question 2 - NCERT Exemplar - MCQ - Chapter 6 Class 10 Triangles

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Transcript

Question 17 In the figure, if DE∥ BC, AD = 3cm, BD = 4 cm and BC = 14 cm, then DE equals (a) 7 cm (b) 6 cm (c) 4 cm (d) 3 cm Since DE ∥ BC ∠ ADB = ∠ ABD ∠ AED = ∠ ACB Thus, by AA Similarity Δ ADE ~ Δ ABC Since sides are proportional in similar triangles 𝐴𝐷/𝐴𝐵=𝐷𝐸/𝐵𝐶 𝟑/(𝟑 + 𝟒)=𝑫𝑬/𝟏𝟒 3/7=𝐷𝐸/14 3/7 × 14 = DE 3 × 2 = DE 6 = DE DE = 6 cm So, the correct answer is (B)

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.