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In Δ DEF, AB ∥ EF. The value of… (Class 10 Maths 2026, Q3)

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MathsCBSE Class 10 · Standard · Board exam 2026, set 30/3/1 · 1 mark · MCQ

CBSE Class 10 Mathematics Standard 2026: question 3

Set in the CBSE Class 10 board exam of 2026, paper 30/3/1, section A, question 3, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q3 · 1 mark · MCQTriangles

In DEF, AB EF. The value of x is :

  1. (A)0, 2
  2. (B)2 only
  3. (C)-2
  4. (D)1

Figure in the paper: Triangle DEF with A on side DE and B on side DF; AB is parallel to EF. Labels: DA = 2x, AE = 3x + 1, DB = x, BF = 2x - 1/2. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 30/3/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

A line parallel to one side of a triangle divides the other two sides in the same ratio.

Hint 2

Write and solve. Then check which root makes sense as a length.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Since , BPT gives , that is .

  2. Cross-multiply: , so , giving or .

  3. would make , which is not possible for a length. So only, which is option (B).

    1 mark

Answer: x = 2 only; option (B)

Where the marks are

  • Chooses option (B) 2 only (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Triangles, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 30/3/1 (Standard): every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.